I hope I don't come across as too patronizing, but Amex cards do trip end users up sometimes- the CVV number being 4 digits, and on the front of the card, unlike Visa & MasterCard... I've personally made the mistake of reading the wrong numbers off my Amex cards a few times.
Ha ha, not to worry, I did use the four digits on the front. This is my primary card. They have a "what is this?" too to look at and help with the CVV that corresponds exactly to my card.
