Trouble with coupon codes in Payment form

We are having a problem with the coupon codes working for everybody. When they enter it, it does not deduct the amount when they transfer over to PayPal.

I have tested form that is embedded to your website and I noticed that payment fields inside of your form are not showing total amount when I choose some products. 

However form is working fine when it is not embedded.

This is probably happening because you have embedded your form with script block (source code) to your website. We recommend  using of iFrame code. You can try to replace source code with iFrame to see if the payment field will work correctly. In this article you can find out how to do it.

http://www.jotform.com/help/148-Getting-the-Form-iFrame-Code 

Hope this will help. Let us know if you need further assistance.