Garden faucet silcock to PEX line connection

Good evening and thank you in advance for replying to my first post! I didn't have to worry about plumbing issues until now that I bought my first home.
Anyways, I am trying to install no freeze silcock. The main water line is 3/4" PEX. I put T connection with 1/2" PEX line going to the silcock. The problem I am having is that the silcock is leaking from what appears to be brass connector. It does not leak from the PEX line end. Replaced the connector, it sits tight with teflon tape but still leaks. Thank you!

So you have a fitting something like this I assume?

1/2"male PEX end x 1/2" FNPT(female pipe thread)

End of no freeze silcock with 1/2" male thread that requires this fitting to go to the 1/2" PEX?
And it's leaking at the arrow? Between the silcock end and this fitting?

Hmmm...must assume you tried tighten it down a bit more. I'm guessing it's in a location that's not the easiest to get at.
The only thing that comes to my mind is the male threads on the end of the silcock male have been damaged. You would have to disassemble AGAIN and look at it.
In the mean time, did you happen to put a dedicated shut off valve on that line to the silcock? Just thinking that if you had to remove it again to try to fix it or for any reason in the future, it allows you to isolate it without shutting down anything else in the house.

Maybe someone else may know something that would help.