Loot Card Already Redeemed

I bought some WoW trading cards last night and received a loot card for a Tiny Mount. The card had been untouched of course, as I had just bought it. When I scratched off the cover to the code I went to the redemption page and entered the code for the mount for the realm Wildhammer. As soon as I did this the page directed me saying the following:

Your promotion code has already been redeemed for a promotional item on the realm "Perenolde" (Europe).

I figured I had entered the code incorrectly, so I proceeded to enter the code another 4 times to make sure. Each time it came to that response. I'm at a loss here as this card has been opened by myself and myself alone and it is impossible that it has already been redeemed. (I bought the cards at Wal-Mart, not online where someone could have redeemed the code and then sold me the card).

Again, this card was sealed and as soon as I attempted to enter the code it states that it has been redeemed in a European realm, which is also strange because I bought the card in the US and play on North American realms. I would like to know what I can do to obtain this mount that I am entitled to seeing as how I purchased the card from a legitimate business, yet somehow it has already been redeemed.