Incompitable Game Data.

hey.
ive bought an russian mw3 retail key.
i installed via cd a full german version.
now, when i want to join a server, i get the incompitable version error.
where is my bad?

well, what do you think?

Right click on Modern warfare 3 single / multiplayer in steam, go to "proprieties", then go to the language tab, and select german for single if you want to play in german. Unfortunatly for you, the russian version only include english / russian languages, so you'll have to select english in the multiplayer (unless you read russian). Then steam should download back somes files. You can also do a cache verification in steam if the issue is not solved after the first solution.