Photoshop Elements 11

I purchased this today from my local Walmart, they were having issues with the product ringing up so they had to key the item in, during that process it did not ask them to scan the activation code, so when I try to type in my redemption code it tells me I cannot use it. what do I need to do to get this working, all copies they had did this and they couldn't figure out why it wouldn't let them do it?