Got the Droppers so Where are the Trout?

There's not a drop of wind and the lake looks stunning. Two other people there but they are on a boat so I can't interrogate them. I take the small agile boat and head out to the far side of the lake.

I'm testing my new droppers. (a dropper in an extra fly or two or three added to your like)  I've been watching Hywel Morgan on Sky ( Hywel Morgan ) he seems to fish with droppers all the time. So on his advice I create just 1 dropper to start, 8 inches long and 50cm up from the end fly. I'm concerned that I will struggle to cast this without tangles and I prove myself correct, I'm starting to think I need a lesson. No fish with that so I switch to my normal set-up.

There are fish around but they are not taking from me! I use buzzers, dry flies, damsel nymphs and many more - its frustrating and I feel like my casting is very poor today - again I think I need a lesson. This is what happens when you watch a pro like Hywel, I feel like a total amateur.

Eventually a get a take on a nymph looking thing, pulling it below the surface. I'm really pleased and feel that my day has been retrieved.

I row around the corner and there is one of the other people. He says to me that he has caught 3 trout already and they are going mad for his dry Damoiselle fly. 'Just cast it in and they are gorging themselves - go on give it a try'. So I throw out the anchor and put on a dry Damoiselle. These have not worked for me in the past and this didn't work for me today. In the 20 minutes that I was there he pulled out another 3 fish! All on the same fly - what am I doing wrong? I need to know!