I am concerned that my payment process is not flawless.

I am concerned that my payment process is not flawless. I am using PayPal Single Payments Gateway . When someone signs up and they use their own paypal account, they receive a receipt. When they are not a paypal member, they use their CC processing and they do NOT get a reciept. This is a huge concern. How can i get this system to work so there is no gap in the payment process?