Why I am getting "missing recipient" error message?

When I try to set up an autoresponse for one of my payment forms I'm getting an error message "missing recipient". There is a dropdown menu with the label "recipient" but there are no choices. Further, I don't understand why I need to choose a recipient when I am creating an autoresponse since the autoresponse should go to the person completing the form. I don't have this issue with forms that don't include a payment module.

I don't understand the error. 

It is required to choose the recipient email address for the notification/auto-responder. There may be possibility of having multiple email address fields on the form or you may want to send different auto-responders to different email addresses provided on the form.

I have cloned your JotForm to my account and when I tried to create an auto-responder, it displayed all the fields on the forms normally for the recipient field. 

Please try adding a new auto-responder on your form and then choose the email address field as the recipient in the Recipients section.

Please get back to us if you need any further assistance. We will be happy to help.