Check if the cables are connected to the correct ports in the radio receivers and on the EXCON. The radio receivers
only work if they are properly connected. The cables run from the port on the EXCON – labeled Radio – to the port on the radio receiver – labeled IN.
Then the next cable runs from the other port on the radio receiver – labeled OUT – to the port on the next radio receiver – labeled IN.

Check whether the connectors are properly plugged in.