I purchased some of the red plastic one-piece poultry nipples. when testing them out before installing, they are all leaking. upon searching for this, i've found where people asked this same question, and people suggested using silicone, an o-ring, etc. Let me head you off at the pass. It's not leaking due to installation issues, it is leaking water out of the nipple itself. i put teflon tape on the threads, and it is sealed great, the nipples themselves are leaking. is this normal? i'm wondering now if maybe the system needs to be under some amount of pressure to seat the mechanism better? any advice? Thanks!