It all depends where you were fishing ie. what lake, where at that lake, where is the lake located etc. When you say "trolling" I assume you mean that your friends were trolling with wedding bands and other attractors. Trolling is the act of slowly "dragging" a lure (a fly, wedding bands etc) in the water at specific depths, (hopefully where the fish are!) I've caught trout on a micro leech while a buddy of mine had about 5 ft worth of spinners and wedding bands on his spincast, he caught nothing. That's not to say it can't happen the other way, which it has with me and him. If you want to fly fish you will need to find out what the fish are feeding on. What is in the lake to feed on? What time of year is it? Where in the lake are you fishing? All these things contribute. I hope you find this helpful and don't hesitate to ask questions.
Doug