I own a 6unit apartment building. When the upstairs shower is used, the ceiling of the bathroom immediately below drips. I opened up an access panel below to verify. The only times it leaks is when the shower is used.... not when the water is coming out of just the spout for a bath. All the caulk looks good, drain below looks good. Anything else it can be than besides the pipe going from the valve body to the shower head? Its a Union Brass/Union Gopher 2 handle deal. Thanks!!