Last year, there was a glitch in the system, and they required us to enter a "-" (dash) after our AADSAS ID number/CAS ID number so that the payment could go through. They sent us an email with the following:
THERE IS A GLITCH IN THE CREDIT CARD FORM SO YOU MUST ENTER A DASH AFTER YOUR AADSAS NUMBER IN THE DESIGNATED FIELD SO PAYMENT CAN BE ACCEPTED.