Fatal error

I have been trying this module on Drupal 7 without success. Just so I can attempt to fix the Drupal 7 version, I installed a fresh Drupal 6 site with UC_EPDQ and all the other necessary modules to see how it works ... but I get the same error.

In both cases the error occurs when I attempt to pay of product. The error is as follows:

Sorry, there has been a problem processing your payment.

Encrypted data not present.

Can anyone help, please?