DMX LED should be on. If not, check DMX connectors, cables to see if link properly. 2. If the DMX LED is on and no response to the channel, check the address settings and DMX polarity. 3. If you have intermittent DMX signal problems, check the pins on connectors or on PCB of the fixture or the previous one. 4. Try to use another DMX controller. 5. Check if the DMX cables run near or run alongside to high voltage cables that may cause damage or interference to DMX interface circuit.