PayPal Single Payment Gateway Not Working

Hello,

I've been working on implementing your plugin for a week now, my latest problem is with the PayPal Single Payment Gateway.

When people register for our site, then go to subscribe to paid content, such as this:

http://cohe.humanistinstitute.org/courses-family-topics/

Once they get past the login window and click on Subscribe - they ARE redirected to PayPal but there doesn't appear to be any way to pay without creating a paypal account.

I've used paypal with other sites and plugins and never run into this.

Please advise.