A couple of suggestions.

1) I have found that turkeys will respond to calls better if they are coming up hill. You might try getting on the higher ground. This isn't always the case, but sometimes makes a difference.

2) Try just one hen and one jake.

3) All else fails (normal calling tactics) , get set up in a blind w/ one hen and one jake. Call your brains out for 2 or 3 mins and then put the call away for at least an hour. Even if you see one heading your way, resist the temptation to cluck or purr. Be completely silent. Curiosity may get the better of them. Give it an hour and then try again. I have found that this technique is deadly in areas where turkeys are call shy. It gets their attention and they see the decoys, then eventually they come see what the commotion is.

4) Wait a week or two. The dynamics of the flock will change as some of the girls get bred. The tom's will be far more vulnerable to the decoys as there are less ladies for him to talk to.

Good luck.
R
Hank