Hi. I built a paypal shopping cart in a custom html website here www.opiperakias.gr The problem is that none of the website visitors who would like to set an order, not complete the online payment via paypal or credit/debit card. This message appears on their screens (desktop and mobile): Your credit card is declined. Please try another one. I assume that something wrong there is with the source code. Do I need to add or delete something or anything?
