PSA and PDT pilots are listed in the database as US pilots.
When you check in for a CASS jumpseat, tell them you're USAir, and give them youy 6 digit employee number. You'll add a 0 to the beginning if its a 5 digit number. Add your airline code at the end of it, and that should get you through the CASS process. (i.e. 012345JS)
If that doesn't do it, it could be an internal problem with the server Delta is using. In that case, you need to get your jumpseat committee to contact DL and get it sorted out. We had that problem with AA. They were quick about fixing it.