amazon say that because the release date isnt til tomorrow the 26th that could be the reason why it wont activate. will have to wait til tomorrow to give it another go. will be on here trying at 1 minute past 12 lol
It is not the copy of the game that stops the activation, when the code is entered the installer sends a 'message' to steam. With this message is likely the IP address of the person activating their game. This shows their location, and that determines whether steam will activate it.
I just recieved my game and entered the code and it was denied with the message; "...this product is not available in this country..." . I entered it a second time and it worked fine.