Thats why its called turkey hunting and not turkey killing. Seriously, I am not an expert but here are a couple of thoughts. Do you go at about the same time of year each time? Turkeys change their behavior as the breeding season progresses. Early on, the Toms gobble on the roost to attract the hens. If the hens show up he will fly down to them and you are pretty much out of luck. You may be able to get a subordinate gobbler that is wandering around but he may not gobble much. Your best chance under those circumstances is to get real close to them (within 100 yards if possible) while they are on the roost and try to call them in before they get to the hens. You can use some tree yelps and soft clucks and then a fly down cackle. You might get lucky and he will pitch down thinking you are the first hen to hit the ground.

Later in the season the hens start to go to the nest and the gobblers will gobble more during the day and be more receptive to calling. Also, if you can locate their strut zones that will be a good place to hang out and call a little.

There are a lot mor options but hopefully some of this is usefull.