Using PINpad 1000se with IC-Verify and First Data

Question

We are trying to get debit cards working on our system, which uses a vb.net program to extract the data from the pinpad and send this to IC-Verify/First Data. When we run our transactions thru IC-Verify's GUI interface, we get an acceptance. When we run this through our programs, we get a Pin Error message. We are sending them the 16 digit keyed serial number and the 16 digit encrypted pin. IC-Verify states our format looks correct, but they do not know why we are being declined. They suggest it must be in our formatting??
Any help would be appreciated.