Cant process payments though authorize.net

my payment form is not working. Can you tell me why?

http://www.dring.com/make-a-payment/

I have tested the payments through Authorize.net using my sandbox account and see that it is working fine at my end. Are you still experiencing the issue with the payments on your form? Please try removing the payment field and add it once again to see if that works. The issue might also be with the credit card being used in which a different card can be tried.

Let us know if you need any further assistance. We will be happy to assist.