Chess Assistant 17 & Chess Assistant 17 PRO
Chess Assistant 17 combines advanced game database management, analysis powered by the strongest Houdini 5 engine, the advanced Tree mode, Opening Encyclopedia and many other features.

Chess Assistant 17 with Houdini 5 — $94.95 / €75.96
Chess Assistant 17 PRO with Houdini 5 PRO — $145.95 / €116.76 » Most Common Technical Problems FAQ

Frequently Asked Questions (FAQ):

(last updated December 1, 2017)

Q: How to activate my bonus Chess King Learn subscription?

A:Follow the Chess King Learn bonus sub activation guide.

Q: During installation i get an error message: “A newer version of Microsoft Visual C++ 2010 Redistributable has been detected on this machine”.

A:Ignore the message and run Peshka.
You have the newer version and Peshka will work fine.

Q: What are Lomonosov Tablebases? Are they better than Nalimov Tablebases? How to access them?

A: Lomonosov Tablebases allow you to determine if any position with 7 or less pieces leads to a draw or can be won by either side - with 100% certainty. Nalimov Tablebases only allow to do this with up to 6 pieces on the board.
Refer to this page for more info.

Q: I installed the Rybka 4 Opening book on my new ChessOK Aquarium, but the new opening configuration is not created. What is wrong?

A: The current version of ChessOK Aquarium has some issues with older Opening books. To fix the issue with Rybka 4 Opening book, install it, then download the Rybka4_book.xml file and save it to the ..\aqaurium2012\Data\Config\TreeСonfig\.. directory.

Q: I bought the download version of Chess King, but now I’m having troubles downloading such a big installation file. Can you help me?

A: Yes, we can. Write to our technical support ( and we’ll tell you how to download it in 3 files of smaller size.

Q: Where can I get login and password for automatic updates in Chess Assistant 12?

A: To get your login for this function, send an e-mail with your serial number to Your serial number will be your password for automatic updates. Don’t forget to include your serial number, or we will not be able to send you the login.

Q: What is the difference between Houdini 2 Aquarium and Chess Assistant 12?

A: Houdini 2 Aquarium is primarily a tool for playing and analyzing. It has various playing modes, including with material, rating and other kinds of handicaps; advanced game analysis functions with different tree presets etc. Chess Assistant 12 is a multipurpose product combining powerful playing and analyzing modes with broad options for databases and Chess Opening Encyclopedia. Both programs include an up-to-date database of more than 5.2 million games (as of October 1, 2011) that can be updated weekly from

Q: Do Chess Assistant 12 and Houdini Aquarium include the UCI version of Houdini?

A: Yes, both Chess Assistant 12 and Houdini Aquarium include Houdini UCI. After installation, Houdini UCI and its documentation can be found in the following folders:
“Chess Assistant 12 / Houdini 2 Chess” folder for CA 12
“Houdini Aquarium/ Data / Engines / Houdini 2 Chess” folder for Houdini Aquarium.

Q: Where can I find the free database updates mentioned during the Houdini Aquarium release?

A: Database and other updates can be downloaded from the Free Game Service page.

Q: How do I activate download courses for Peshk@?

A: Detailed instructions and a video guide can be found on this page.

Q: I cannot install Jeroen book 3 and Aqaurium book 4 into the new Houdini 2 Aquarium

A: Houdini Aquarium goes without two files: Rybka4_book.xml and Jeroen_Book.xml. Please download the files:
and put them to the [aquariumdata]\Config\TreeConfig\ folder. The installed versions of Rybka3 and Rybka4 books should now work.

A patch fixing this problem for Houdini Aquarium will soon be released.

Q: Aquarium says my serial is invalid when I try to copy/paste it. What’s wrong?

A: There’s a behaviour of Windows 7/Vista that often changes the ‘-’ (minus) character for a similar, but different dash character when you copy/paste a serial key from clipboard. This can be solved by manually typing the serial, or manually replacing the dashes with a ‘-’ (minus) sign. We’re going to implement a fix in a future updates.

Q: I get an error message of “Failed to set data for “CA Chess (True Type)”. Chess fonts do not display properly. What should I do?

A: When running the installer under Windows Vista/7 you will be prompted to select installation path, by default C:\Program files\ .
We highly recommend to change installation path to some folder outside of Program Files, e. g. C:\\ This is likely to solve the problem in 90% of cases.
Also, try using standalone installer of chess fonts. Download and run it with administrator rights (open local menu on icon on desktop and select “run as admin” option).

Q: I inserted activation link in “activate course” tab in Peshka and got “no new courses” message. What’s wrong?

A: This means that this course already activated. If you don’t see this course in “show courses list” tab, send your activation link to technical support at and we will try to resolve the issue.

Q: How can I install CT-ART 4.0 or other Peshka training courses?

A: Follow this guide.

Q: How do I upgrade CT-ART 4.0 (download version)?


  1. Download and install the latest version of Peshk@.
  2. Run it.
  3. Open online course browser.
  4. Browse for CT-ART 4.0. You should see “Update now” button next to it.
  5. Click on “Update now” button.

Q: How can I run older versions of software under Windows Vista/7?

A: Note: these recommendations are only applicable for previous generation of software by ChessOK. If you want your software to run smoothly, please follow the instructions below.

  • After running the installer you will be prompted to select installation path, by default C:\Program files\<program name>.
    We highly recommend to change installation path to some folder outside of Program Files, e. g. C:\<your program name>\ This is likely to solve the problem in 90% of cases.
  • Another option is to install to >C:\users\your_program_name<
  • If you still experience problems when running the program, we recommeding switching User Account Control off:
    • Click on Start -> Control Panel -> User Accounts
    • Find Turn User Account Control on or off
    • Turn off “Use User Account Control (UAC) to help protect your computer
    • Press “OK”
    • Reboot if required

Q: I’ve bought a CD version of CT-ART 4.0 (or some other training course). I then upgraded it or installed downloadable version of Peshka and my course suddenly stopped working. What to do?

A: The downloadable version of Peshka has to be installed seperately in order for the CD version to work properly. Reinstall it in a different folder.

Q: I have a problem running Aquarium 2010 under Windows XP. What can I do?

A: Install these libraries from Microsoft.
Link on the same file on Microsoft site

Q: I can’t login into Peshka or ChessOK downloader. What happened?

A: ChessOK Downloader and Peshka share logins and passwords. So changing your password in one program would change it in another.

Q: I can not install Jeroen’s Rybka Opening Book in Aquarium 2010. Is there any fix?

A: You need to redownload and reinstall the updated version of the book. You can download the updated book from there using your serial key. If you’re unable to download from this link, please mail to to get the link.

Q: I have a problem running Chess Assistant or some older (non-Peshka) training software on Windows Vista/7 due to User Account Control. What can I do?

A: You may need to reinstall the software or disable User Account Control. Read more in this guide.

Q: Do you have any software for Macintosh computers? Can Rybka be run on MacOS?

A: Only Dinosaur Chess for Mac. We are not aware of any solutions that make our software runnable under MacOS.

Q: I have a problem with chess fonts in your software, how do I install chess font?


  1. Download chess fonts from there.
  2. Open Fonts dialogue:
    • Windows Vista — Settings\Control Panel\Fonts
    • Windows XP — Control Panel\Fonts
  3. Select Install New Font via File\Install New Font (if you don’t see menu press Alt key)
  4. Install the font:
    1. Select folder where you have downloaded the font in the Folders box.
    2. Select CA Chess font
    3. Click Install button

Q: When I tried to download file using ChessOkDownloader I received the message “Unsufficient rights”. What should I do?

A: You didn’t provide your serial number or provided invalid serial number when started ChessOkDownloader.exe.

You need to click Yes to enter your serial number. If you clicked No you need to enter serial number later. Use Options button for this.

Click Register serial number

Provide serial number

Q: I can’t use your Winhelp files in Windows Vista, what to do?

A: Download patch for Vista from this link:

Q: I can’t link DGT electronic board in Chess Assistant. What should I do?

A: Some Chess Assistant packages do not include DGTEBDLL.dll file. So working with DGT board is not possible. If you have DGT board and unable to link it please put this file into your Chess Assistant folder.

Q: How to add Rybka 3 UCI to Shredder interface?

A: The Shredder interface requires file names without any blanks.
You should delete the blanks from the Rybka filename before installation.
For example, “Rybka 3 1-cpu 32-bit.exe” can be renamed to “Rybka31-cpu32-bit.exe”.

Q: I follow the instructions but I can’t link Rybka*.exe to Fritz, what’s the matter?

A: If you have connected Nalimov Tablebases to Fritz then try to do the following:
1. Put the exact tablebase path in “Extras/Options” of the Fritz GUI,
when Fritz is the active engine.
2. Quit the Fritz program totally.
3. Start Fritz again. It will now have Fritz 9 as active engine.
Tablebases are working. (Try!)
4. Deactivate the path to the tablebases, for instance by changing
“Nalimtbs” to “Nalimtbs0″. (So you don’t have to seek the path
afterwards again.)
5. Load the Rybka engine. The will be no error, and Rybka will use the
tablebases now.
6. Before quitting the program, change again to Fritz 9 and rename the
tablebase path again correctly.
7. Next time start with 3.

Q: Why does Fritz (or another well-known strong program) calculates more variants (plies) in a second than Rybka (and sometimes much more than the latter)?

A: Rybka is a positional program. It calculates fewer variants, but does it more thoroughly. Moreover, the quantity of variants in a second is not the main indicator of program’s force.

Q: How many processors does Rybka multi-processor version support?

A: Rybka multi-processor version supports all processors. However the 8 processors are used with the most effect.

Q: How to adjust the program Rybka to make it play in the strongest way?

A: For default all settings of Rybka are the best. You may increase its strength by adding more RAM for Hash tables, adding Nalimov Tablebases, using more strong Opening Book or using more powerful computer.

Q: I changed computer equipment and reinstalled Windows. Your programs won’t run. How to reactivate CA10 or Rybka?

A: If you bought version on CD/DVD, then you should reinstall it.
If you bought Rybka & Chess Openings (download version) or Chess Assistant (download version) and you have got the message: “This software does not accept more hardware changes. Please,contact” from win license protect, you need to delete ca10.dat (CCo.dat) and run program again. It will open the window for activation. Enter your serial number and select activation by Internet or by e-mail.

Q: While installation I have got the message that entered serial number is not correct.

A: There are two possible variants.
First, the serial number is entered incorrectly (for instance, the hyphens between figure’s groups are missed or the figures are replaced while entering). The second variant, that you try to use serial number of one program or version of Rybka & Chess Openings while installing another version. You can check, whether you serial number is correct by writing to

Q: What is a chess engine?

A: A chess engine recommends moves and provides evaluation scores for chess positions. It should be used together with a chess graphical user interface (GUI), which will provide intuitive graphical interaction with the engine.

What graphical user interface should I use with Rybka?
The major chess graphical user interfaces (in no particular order) are:
· Aquarium
· Arena
· Chessbase/Fritz
· Chess Assistant
· Shredder
· Chess Partner

We recommend Aquarium.

Q: Does Rybka come with an opening book?

A: Yes. Rybka’s commercial opening book is written by Jeroen Noomen. You can buy version for Aquarium there.

Q: I bought Rybka UCI, but it won’t run.

A: Rybka UCI is not standalone program. You need to download it to the hard disk and add to any other chess program (which supports UCI protocol). Instructions here.

Q: How can I make an order with Convekta?

A: There are several options for you to choose:

1. Make an order at our webstore
2. Make an order by fax: +44-1628 486777
3. Make an order by phone: +44-1628 486676

Q: Is Encyclopedia of Middlegame Vol. 1, 2 & 3 included in Total Chess Training or just Volume 1?

A: Both Volume II and Volume III are not included in Total Chess Training.

Q: I ordered a book and a program at I received the software almost immediately, but still no book. Can you please advise?

A: We have got several our chess stocks located all over the world which is aimed at reducing delivery costs. Thus components of an order can be shipped out separately from different places in separate packages. The program you ordered was sent from one of our stocks while the book was shipped out from the other one two days later. That means there is no need to worry so far.

Q: Can I order by phone? Is there a number I can call to place an order or a catalog?

A: Yes, you can order by phone. Please try the following phone number:
+44-1628 486676

Q: Can I place this order by simply faxing you my credit card details?

A: Yes, you can fax your credit card details to the following number:
+7 495 930-18-87
+44-1628 486777

Study chess online on Chess King Learn! Time-proven training courses, thousands of examples and exercises.

Start playing right now in your web browser on Chess King Playing Zone! Teams, tournaments, training, analysis and much more!

7-man Lomonosov Tablebases provide deeper-than-ever insight into chess endgame.

Download weekly chess database updates (containing 2000+ games) with latest tournaments and games in PGN and Chess Assistant format.

More »