There could be several reasons why a credit card is being declined:
Reason 1: Make sure credit card number, expiration date and verification code are correct.
Reason 2: The denial reason being returned from your credit card company is "Address Verification Failed." It would appear that the address you're entering doesn't match that one your credit card has on file. A suggestion would be for you to try another credit card or contact your credit card company to get a better understanding of the error message.