won't let me register demigod

every time I click register it says I don't have the correct serial number.  is there a different one other than the number on the back of the book?  and when I try to verify my installation, impulse says that it's installed incorrectly and that I need to update, but I can't update since it won't accept my serial number.  I just bought this game a few hours ago, so what's going on?  I tried this on two different computers with the same result.  so it's not a mess up with the installation.