The key on the CD/DVD sticker isn't the one you can use to register the game on Stardock - you have to use it to register the game on Russian official site. This would allow you to receive the Stardock key and register the game to play online, etc.
The clear explanation of this process is given in the electronic manual; direct link to registration page is present in the Start menu. If you any trouble with this, please e-mail Snowball Tech Support ([email protected]) or you can their forums http://www.snowball.ru/forums/?board=tech