I read Jay Smith's "Better Queens" (thanks Michael) and got a sheet of foundation built out (btw the 2 times I've done it mine seemed to stretch with the weight of the bees on it) put in with the queen and two full frames and she duly laid enough eggs in it. I then put her hive back together and put the frame with eggs in the top box above an excluder. When I came back days later, all ready to cut the cell strips but all the cells that had eggs in them before were empty! What went wrong? I'm not sure if there was open brood beside them when I stored them above the excluder I will ensure that happens next time, but is there something else I'm missing?