It's not his bank. I'm getting the same error when I try with a debit card and the promo code.
I tried pulling it directly from checking account, also with promo code, and it accepted the transaction (so far), but with a 4-day delay. There is always the possibility that they will later come back and tell me the bank declined the transaction, blah blah.
Millie, were you using the promo code when they declined your transaction? Was it with debit card? Jblaze, how about you?