"The transaction resulted in an AVS mismatch."

Some of our customers are getting the error message above. Has anyone confirmed is this is a bug in this module, or is it simply the customer that is failing to enter all information correctly? I see that in authorize_net_form_validate(..,..) the only data that is validated is the CC number, and not address and/or name. So I guess an empty name or address line could slip by seemingly unnoticed and cause this error..?

Thanks,
Andreas