It might be worth contacting Paypal to see if they have any sort of block on your account or on taking payments - that may just be down to the type of PayPal account you have. The error is coming from them rather than from the software.
I had asked PayPal to drop the Virtual Terminal as I had no need for it. I thought I was paying extra $30 a month for this.
The person I talked with on this didn't tell me that VT is part of the PayPal Pro. So when this change was made I lost the transparent transactions which is coded in the website.
Took 4 days and that many or more phone calls to get them to put it back the way it was. Finally working correctly.
Walt
www.rustystumps.com Manufacturer of fine scale model railroad kits and detail parts