All 3 way switches have only 3 wires going to each switch. I have an exsisting switch and it has 5 wires going to it. 1 white, 1 red, 1 black, and 2 grey/black. these switches control a ceiling light. The light will turn on at the lower switch and off at the upper switch, but I can not turn the light back on again at the lower switch until I flip the upper switch. What am I missing in my hook up, and why are there 5 wires?