I have added the PayPal add-on to a client's Gravity form. Transactions are going through and I have also had success testing the form as well. However, some visitors to my client's site are claiming that upon clicking "Submit" they are not directed to PayPal and merely get the "Thank you" message, yet their payment obviously is not going through. Do you know anything about this issue? Might there be an issue with some browsers? Can you point me in the right direction as to how to possibly resolve this issue?
http://txaee.org/?page_id=16