To tell you the truth, i have no idea. Have you pruned them and kept them watered. We've had some pretty dry springs over the last few years. Did they actually flower back in May ???
Most fruit trees have a 'lazy year', at some point, if all three are fruitless at the same time, then I would guess, as andyjevs has said, did you prune them?, I have a mature, massive, apple tree, and two years back, gave it a 'hard prune', its only now stating to fruit again.