Old Bathtub Drain Prob

I have ancient bathtub on the second floor where the drain was leaking so i replaced the crap there with pvc the only trouble there is a 90 degree connector that connects directly to the tub and it has a thin brass pipe that srews directly into it .....the threads are very very fine as well as short....(about 3/16 to 1/4 inch long) i doped it up and tightened it all the way and i am getting a small drip .....i did notice when i took it off it has some hardened plastic blue stuff around it.....was this plumbers epoxy?

should i put some of this plumbers epoxy around the joint to seal it off?

thanx

also very stupid question here.....do u guys tape compression threads on drain stuff (pvc or brass or even that chrome) before tightening?

If by "plumbers epoxy" you mean pipe dope, that is a very common item to use on threaded connections...
You should use it or teflon tape when making up a joint where the threads seal...
As for compression joints...
The teflon tape will hinder your tightening them... It is not the thread that seals the joint on a compression fitting...
It is the ferrule on the pipe that forms the seal between the pipe OD and the fitting - the threads simply allow you to apply force...
A bit (very little bit) of non-hardening pipe thread sealant (lubricant) might help in the tightening... It will not help with sealing....

The blue stuff might have been thread locking compound. Try some pipe dope.

this is the epoxy i mean:

http://www.wmharvey.com/prod/cat4/pep/epoxy.php

has anyone ever used this stuff?