Actually, I started thinking about that very same thing after my last reply. Somehow when I installed the PO module, I got it in my head that the variable needed to be added ANYWHERE that data was being posted to the order history table. Thus, into the Authorize.net module it went.

Sure enough, as soon as I removed the po_number references in the mod, all was well w/ the world again.

Thanks again for guiding the way to a poor lost Zen soul.