Like said some where else....it's like elk hunting, if they ain't there, you got to move on. Occasionally they ARE there, but won't make a peep so as not to bring "others" in.
Watched a tom with two hens do exactly that....we were watching them, and when we called, toms over the hill responded, and in fact, come in. The hens/tom combo moved off as the other toms came in. I'm sure that tom with the hens didn't want to share with the others, and I'll bet them toms had seen the lone male with the hens.
I think that is what made 'em come in so readily to our call....take advantage of the situation.