I have been experiencing the same thing, and my only theory is that all the dominant gobblers are with hens right off the roost, and the subordinant gobblers are afraid to gobble out of fear of the dominant birds. but i've heard that once the breeding season ends, its much easier to call one in, because nearly all the available hens have been bred and are on their nests, and the gobblers are trolling the woods looking for a hen. as for your question about the roosting gobblers, get up about a half hour earlier and be in the woods well before first light. they won't switch trees in the middle of the night unless something spooks them bad enough to bump them off. don't try to get too close to the tree, as you will be seen. as a general rule, you don't normally want to get closer than 75 go 100 yards to the tree the bird is roosted in. wait for daylight and don't call until you hear him gobble. when you do, use a flydown cackle, and you can use your hat to simulate a hen flying down from the tree. i normally don't do this, as its a lot of movement when you're set up that close to the bird. if he answers you, a few soft yelps and a little patience should bring him right in. good luck!