I am using zen cart 1.3.8 version with barclays ePDQ payment gateway. I have downloaded the module from add-ons on the zen-cart site. I have done all the things which are necessary to configure ePDQ. The problem is this that when i press Confirm order and it redirects to site https://secure2.epdq.co.uk/cgi-bin/CcxBarclaysEpdq.e
and shows following error :

Sorry, there has been a problem processing your payment.

Unable to read configuration file.

Please let me know how to resolve this issue?