http://making-history.com/forum/thread/390083/1

"We just found out that a batch of the license keys with the German language version of the game are invalid. We have a process in place to get valid keys to customers - just email the key that came with the game to techsupport@muzzylane.com. We apologize in advance to anyone who runs into this issue and want to get you playing!

Update: Version 1.22 includes code that can detect the bad keys and will retrieve a new key for you from making-history.com. Just update to 1.22, enter your key, and you should get a new, valid key. You may also feel free to still email us for a new key if that's easier for you."

Einfach ne mail mit dem falschen Code schicken, dann bekommst du einen gültigen.