Customers cannot pay me via website after upgrading PP business account

[Pelvery37]

I just upgraded my PP account to Business so I can accept Credit Card payments from my website store.
Now I can see that there are lots on pending order and customers say that they were not able to complete the payment via Credit Card or with PayPal account.
I have like 40 unsuccessful orders and 3 successful (I don't know how).

How can I check whats wrong with my account now. How to fix it? I have Stealth PP