use a dmx tester to check if there are any signals on the channels used. I have also the same sort of problem with 2 njd preditor lamps which when i connect them up to my jands desk the lamp on/ blackout relay clicks, just like the is a small signal getting through. have checked the cannels and there are no signals! I wonder if the unit recevers are not quite up to quality and pick up something.?? if you find anything let me know. Good luck.