paypal express not working new customers

[tenerifetom]

i have a strange problem with the paypal express mod when a new customer uses the paypal checkout the customer is taken to the paypal site as normal makes the patment then gets returned to my check out prossess and logs off thinking he has made the purchase but on checking his paypal account no money has been paid.
in my admin area his order is their but the payment method states credit card not the usual paypal. infact i have disabled credit card as we only want paypal.
i have the log files and they look ok but i would not be able to spot where it's going wrong.

the mod does work if the customer exsists on our site db

[DrByte]

That might be something that was fixed in v1.3.9h and v1.5.0