Dblackman,
Looks like you're having the same trouble I was down at my favorite lake. I just couldn't get any fish to bite, however, about every day around dawn and again at dusk the fish started dimpling the surface similarly, I think, to trout feeding on midges. When I finally started fishing when this was going on I started catching fish. My two best flies were an orange humphy and a generic soft hackle. After the rise is over the fish pretty much shut down.
I hope this helps.