Are you using decoys?? I've had some gobblers hang up when the see dekes. They'll sit there...fan out and gobble but they want the hen to come to them. I can't tell you how many times that has happened. I usually go without decoys for that reason. I did use decoys with success this last spring by putting the Buckwing jake right on top of the hen like he was mounting her.

If you aren't using decoys, you could do as others have said and set a guy 40 or more yards behind who does the calling. Also, if you hear him gobble and know you can move without spooking him, try and change locations by maybe moving closer. If you are using only yelps then switch to really soft clucks and purrs. I had a Wisconsin gobbler a few years back that gobbled in front of me on the edge of the woods but wouldn't come out. He went back and forth as I yelped softly. Then I went silent and reached down and clucked so softly that I could barely hear it. Suddenly, he gobbled much closer. I couldn't see him as he came but followed his footsteps with gun barrel. His head and body came into view at about 8 yards and the game was over. If I'd have kept yelping he might have taken off or gotten spooked. I've since went to only soft clucks/purrs when they are close and it has worked well.