I'm having the same problem with a PA Partnership return with 2 nonresidents and its not calculating the balance due, I activated the schedule NW after I indicated on the K1 worksheet for both partners to file form PA40-NRC, then the amount due showed up but I cant pay it electronically. I was on hold over 50 minutes and gave up and went home. Ive spent to much time on this problem. Every year it seem that Penna returns are a nightmare to figure out