still problems connecting with Paypal

I got back with Paypal, and all is fine on my side with them. they said it was with the "3rd-Party" (you) guys. i am sure there is something i have not click properly, can you go over everything again please? I have had several "error" messages, not the same ones. sometimes it does connect with Paypal.
i saw something about having "pretty permalinks' over "default" ones… what does that mean?