Making up tub/shower tree for new one piece unit. Using CPVC. My glued connections are great, but the CPVC to brass fittings are leaking where they connect to the Moen 4 way valve at control. Tried 2 wraps of tape, also tried good amount of teflon compound only. I've had to remake the whole setup three times and keep getting small leaks at the threaded male to female valve connections. I've got them tightened till about 3 threads are visible, still no luck. Its driving me bonkers. Its our only bathroom, so I'm under the gun. Any help much appreciated. Thanks.