It is an EU code that's probably why you can't redeem it. I tried from an EU account and it looks like it is still available, I get the following message "This Prepaid Card cannot be redeemed on a PC.". Too bad I'm at work...
I was only kidding about rummaging through the dumpster. But good for you!
Although I wonder if someone actually paid for the codes you redeemed and went home and realized that they don't work :-P