In the process of installing a new basin in one of our bathrooms, I replaced the old valves on the hot/cold inlet copper pipes with new valves. These valves had compression fittings and I took care to put teflon tape on the threads etc and tighten the nuts appropriately. However, when I turned on the water, there was a slow leak from around both compression fittings (hot and cold water lines). Was there anything special that needed to be done to install a compression fitting other than tightening it real good and using teflon tape? thanks......