Just got adobe photoshop elements 12, and it tells me my serial number is invalid. I never got an email telling me I need to redeem it, and the sticker on the back on the CD box is supposed to be the serial code right?

Ok, so I just bought Adobe Photoshop elements 12 from Best Buy a month ago, and I want to download it onto my computer now. So I inserted the CD and everything, and through the process, the box popped up telling me to insert my serial number. After looking up what that was- and being told it was on the sticker on the back on the CD box- I entered it, and it keeps telling me it's invalid. It's a 8 number, so is it a redemtion code? If so, where do I redeem it?