Did the light bulb test fine before you tried this? You said it lit up and then went out as you were turning the switch off.....So, I recycled the power. Light didn't come on. Checked fuse, fuse good. On a whim, pulled the light bulb - blew it up, smoked it and put a hole in the glass.
Is the circuit you are using for the test:
(circuit pic thanks to Doug / GC member "loudtubeamps")