Rick,
Yesterday, I had the same problem you described in one of your stories this morning. I was throwing a tiny (#16?) version of the Hare's Ear Nymph and no matter what I did it wouldn't sink and therefore behaved more like a dry fly than a nymph. The 'gillies ignored it totally.
Partly my fault, I think; I was using a 4X (6-lb. test) leader which is somewhat resistant to sinking anyway due to its larger diameter creating more surface tension flotation.
Three guesses how I solved the problem, and the first two don't count.
Joe
"Better small than not at all."