I have had a real problem keeping mating nucs populated. I have shaken nurse bees, always fed, put in a pheromone, brought the nuc inside for 3 days then out to the mating yard, much to no avail. Most all bees leave if not in fact all. I have about 10% success. Anybody got any ideas what I could be doing wrong. I do better making splits and adding the cells that I graft, but that doesn't help if I want to sell queens.