PCI Error During Transaction.

I thought I had posted this a while ago but couldn't find it when I searched so I'll repost again. 

My customer got an error message when he tried to pay his bill on my website. The message was PCI error during transaction. I did some research and I've checked the API key and it seems to be current. I have also checked the Business Type setting in Authorize.net and it is set to card not present. 

Can anyone shed any light on this issue? The address for my form is:

http://www.pdqlitho.com/customer-payment.html

Thank you,

Annette

This seems to be a duplicate thread regarding the same issue. To avoid any confusion, we recommend posting one thread per issue. Please see my colleague's response on your other thread here: https://www.jotform.com/answers/1037353 

To view your posted threads, you can visit the Jotform forum page and click My Questions.

Regards.