The smart ones will hang up 50 yards or so out if they dont see another elk and just hear the calls. I have heard pretty decent reviews from people using those Montana pop up decoys 20-30 yards behind the caller if your alone. That is also why a lot of guys will hunt in pairs, one calls from 50 yards or so behind the shooter. If your alone and they are hanging up, get on the ground and when you call, right away rush to another hidden spot 10 yards up, and if you get a response call again and rush up and call. Vary it as you see fit but it makes him think there is another bull coming at him so he may come at you more.