I bought the game used via amazon.de, and it seems the serial is already bound to another account. At least the Stardock software sais something about either my email or serial being invalid when I try to update the game, while both my email and the serial on the back of the handbook are correctly entered.

So, what do I do now and what am I missing out on?

Oh yeah, and as I mentioned in the subtitle, this isn't really a bug I suppose, I just wasn't sure where to post this, or where else I could reach support.