I want to wire in a touch control in a wall sconce. I have a control unit and I have done this before, but I'm not able to get the unit to work. The unit I currently have has 4 wires, white black red and yellow. The unit I got previously had 5 wires, white, black, 2 reds and yellow. When I wire in the current unit, I get power to the light and if I touch the yellow signal wire to the light or touch it with my finger, the lamp dims and goes out as it should. But, when I attach the yellow wire to the mounting strap or to the ground wire, I get power, but the lamp does not respond to touch.