Drain leak on new sink

I installed a new bath sink and drain, but it is leaking at the drain tube that is connected
to the new sink. I used plumbers putty on the drain collier that touches the sink.
I then pushed the rubber gasket up to the bottom of the sink, then slid the hard plastic washer on,
then tightened the plastic nut up to the sink, I can see the water running down the plastic
threads of the drain tube. I have tightened and loosened the nut thinking I over tightened it,:confused or if it was to loose, but it still leaks, should I wrap the threads with teflon tape, pipe thread compound or silicon.
What is the best solution.
Thanks
Mark

If you are talking about a lav and a lav drain, then you can use some putty of pipe dope thread sealant on the threads.

Yes it is a Lav and a Lav drain connection, thanks Terry I will try that tonight

Great website