I'm attempting to redeem a code from a twitter give away. The source is extremely trustworthy. When I copy paste the code in it says invalid code. After actually reading the page it is asking for a Game Registration code first. After a few google searches it says that it could be found under the billing history tab. After copy and pasting both the order # and product code of the original purchase and scrolling around the page I haven't found anything that works. What exactly am I looking for when it ask for Game registration code?