I have 6 x spots that are all having the same strange issue. They have all stopped striking lamps. I can hear a short very faint buzz when I try to strike but after that I get nothing. Ive even had a working fixture that I've swapped a lamp into to test the lamp. Lamp doesn't fire so I put the known working lamp and all of a sudden I have the same issue and it no longer strikes any lamps. Can anyone think of any reason why this would be happening. Over a very short time, all 6 of my lights now have the exact same problem.