iTunes says my security code is invalid but isn't
I'm trying to buy something from both iTunes and then App Store. Both say that my security code on my debit card is invalid but I've made sure it's not. I've made sure I have input my card number, exp. date, and card type correctly. I've read that this has happened to people but I need a fast solution! I must download Pages!
MacBook Pro, Mac OS X (10.7.1)