Please contact your bank to find out why they will not authorize the purchase.
481 is a "catch all" error code. If you are using a Visa or Mastercard CREDIT card (not debit), the bank returns the 481 decline code if they think there is a problem with the card, usually an incorrect expiration date or an incorrect billing address. In one case, I was told that the bank declined the card because it had never been used outside of the US before, and when contacted, they did agree to approve the transaction. (My service is hosted in Canada by Moneris, provided by the Royal Bank of Canada and the Bank of Montreal.)