Tried the code
So I added your code to both the pp_checkout_failure.php and checkout_failure.php
when using the express checkout button I got this result
We're sorry
Your PayPal transaction could not be completed. Please return to checkout and try again.
PayPal Full Request :
Paypal Full Response :
USPS Full Request :
USPS Full Response :
when using a cc I got success
PLease advise