Thanks for responding Eric. I placed your debug code on the checkout failure page and i get nothing:
Your transaction could not be completed. ***************************************************
Direct Pay Full Request :
Direct Pay Full Response :
****************************************************
I also added this code:
<?php echo(PP_PayProUK_Result("Full Response")) ?>
and I receive:
RESULT=114&PNREF=<PaypalUK Vendor>&RESPMSG=CVV2 Mismatch: 15004-This transaction cannot be processed. Please enter a valid Credit Card Verification Number.&AVSADDR=X&AVSZIP=X&CVV2MATCH=N&IAVS=N
The Payment Gateway is Paypal Pro UK.