I just ran into this same problem two weeks ago (early Feb) Had a 4-way switch for the main entry I was trying to convert to Insteon. Wired everything as I thought is was suppose to be, powered up, no lights. Multiple test, no lights. Spent seven hours over two days during the weekend and finally gave up. Called a friend that was a Journeyman electrician to help. He laughed, "no problem" and then spent 2-1/2 hours mumbling about why and how and a few explicates. Still no go. Tried an experiment and ran a replacement cord (power cord, male end only, no female) and used it to jump the neutral wire from another circuit to the 4-way. Plugged the cord into another outlet, capped the hot, connected the white neutral to the 4-way and tested. Worked as it should! Late '80s house and all the power runs originated in the ceiling boxes, dropped a loop to the switches, no neutrals. For those that have this set-up, it is possible to jump a neutral from another circuit. All neutrals go to the same bar in the load center so it doesn't matter where the circuit gets its neutral. I had to cut a hole in the wall and add a line in multiple locations, sucks but it does work.