Redeeming codes yet not being able to use them? Billing info

I redeemed a gift card, and now I want to gift an item to a friend. I want to use my gift card for this purchase, but it doesn't seem to want to give me the option since I already typed in the code on the card. What am I doing wrong?

Edit:

Actually, iTunes seems to be doing everything in its power to stop me from going through with this transaction. This is really irritating.