I logged in as usual and noticed two copies of AC3, the original that I played yesterday and now also AC3 (CZ). The thing is that uPlay says CZ is registered and the one I played yesterday unregistered. CZ does not load (but is visible in task manager), the other one wont start since it is asking for a key.

I think that is region locked or something ? if it helps i bought the game from g2play.com and it worked parfectly and a friend of mine have it from g2play too and has no problem with the game .