Trying to trace source of PayFlowPro failure

[dpat]

I'm using Verisign's PayFlowPro setup for management, and am having a load of difficulty trying to debug the reason of the failure.  I get up to the final stage of entering my credit card info in, and submitting.  I get a single, generic error: "Failure in ps_pfp payment processing."  This means little to me in terms of figuring out the source of the problem.

ps_pfp.cfg.php has the necessary PPP_* fields declared and valued.  The ps_pfp.php class process_payment() seems to be the area it's failing on, but cannot get any close than that.  Debugging ideas, anyone?

*Note, I am taking over this project from someone else, so I am presuming that all the pfp folders, files, and certs are in their proper places.