So here is the deal , I had bought a used copy of Sins of a Solar Empire a few days ago and have tried to register , but it gives me this message:

"Sign Up Error - Invalid Serial Number

The serial number you have entered does not belong to the email address you have entered. To register this serial number you must use the same email address in which you used to purchase the game.

If you do not have the game yet please support our hard work by purchasing the game."

So , is there anyway to change or reset this? Or do i need to go buy a new retail copy of the game thats not pre-owned