My one month free trial Gold Subscription ran out the other day, and I've been trying to sign-up with a credit card (MasterCard Debit). It gave me an error the first time I tried, and I just tried again today after my 48 hour trial ran out, and it still gives me the error. It says "Can't authorize payment...etc, etc.." I also tried upgrading on Xbox.com, but it didn't work either. Does anyone know why it's not working? Is it because it's a Debit card?