Any chance this is on 12/24? That's the only day I could find JFK-ZRH not flying (although I just did a quick check). Nothing to do with not flying on sundays, just holiday related.

EDIT: Spoke too soon

From 1/9/17 to 3/6/17 Flight 64 JFK-ZRH is M,W,F,Sa only. Guessing for the season. Then T,W,Th,F,Sa from 3/7/17-3/11/17 and returns daily after 3/12/17.

If ZRH isn't your true desired destination (and were using it as a start/stop place for the rest of your trip) - I'd use this as a chance to open jaw to your desired location. Otherwise switch routes/carriers as suggested.