I am trying to install a 3 way switch for one of my lights in my house. I am using a ZW15S for the master, and ZW3K for the auxiliary switch. When I installed it, I connected ground to ground, line to line (black), load to load (black), neutral to neutral (white) and traveler to traveler (red) for the ZW15S, and neutral to neutral (white), ground to ground, traveler to traveler (red), and I connected the 2 black wires together for the ZW3K. After installation, the master switch could turn on/off the light, and it could connect to my smart things and I could switch on/off the light with my phone, but the auxiliary switch did not control anything. I tried interchanging the wires in case the wiring was off in the walls, and I switched the placements of the master and auxiliary switches. No change. The master (ZW15S) works perfectly, but the auxiliary (ZW3K) does not do anything.
ANY SUGGESTIONS? PLEASE HELP!