May not be that you are using the wrong fly, but one of the following:
- Wrong size (I prefer #17 sulfur/bhpt or #22 zebra midges)
- Too heavy tippet (I use 6X fluoro 99% of the time on the Clinch)
- Too short of a leader (I always use 12' on the Clinch)
- Indicator color (white seems to be much less spooky)
Those are a few of the things I have learned in my years of Clinch fishing, and have found are common issues with novice Clinch flyfishermen.