The device is defective and just plain doesn't work
The device works, but the LED doesn't
The wires are not making a good connection
Can you reliably control devices on one leg from a from a transmitter on the other?
Is that 50A dual pole breaker you hooked up to rated for two wires put pole? I doubt it. Did you read the instructions that say the device is to be hooked up to 15A breakers?