1992 Cutlass Supreme Spark Issue

I have an odd problem. This morning my cutlass
(1992 cutlass supreme 3.1 150kmi) started and ran rough. I figured I had a bad spark plug. The symptoms matched. Replaced them, no good. Checked further, discovered that one of the three coil packs was yielding no spark. (The one on the far right, that fires cyls 2 and 5) Seems simple enough, replaced the coiil pack.
Unfortunately, the new pack ALSO yields no spark!
This is the only work recently done to the car, so I doubt it's a loose connection or somesuch as it has been running just fine for months, and has not been touched otherwise. Everything else in the car is fine, as far as I can tell, just that one coil pack seems to have no spark. Please help me, I NEED this car to get to work!