I have a 4 bulb light fixture which suddenly just went out. I checked and there was power to it. I changed all the bulbs in case one was bad and still nothing. So I purchased a new ballast and installed that. Nothing. There is power to the ballast and power in all the wiring going to the bulbs. So I have no idea what to check for next! Any ideas?
If the ballast is wired correctly make sure the connections to the bulbs aren't loose. You could replace a pair of connectors as a test if your fixture allows.