Turkeys are not automatic and they seldom do the same thing. That's what makes them so enjoyable, yet frustrating to hunt. There are a hundred things that could be causing those turkeys to do other than what you expect. Perhaps they have had a bad experience with decoys in the past and now steer clear of them. Just because you have decoys out doesn't mean the turkeys will come investigate. They could have seen or heard you walk in, you might not be a well hidden as you think.
What did your scouting reveal? Do they have a favored area in that field? How often have you seen them near the area where you are set up? It is easier to call turkeys to a place they already want to go. The right set-up means a lot in turkey hunting. Next time, they may be all over your decoys in the same place. How close are you to where they're roosting? What are the hens doing?
Unfortunately, there is no way to tell exactly what is causing those birds not to do what you want them to. Turkeys are turkeys and they operate on their own schedule. You are already in a good place if you have turkeys using the area. It is just a matter of unlocking the combination.
Are they going the same way every time you see them? Perhaps there is a favored strut zone nearby they a choosing to go to to attempt to draw the hens they are hearing to come to. Maybe they're already in that strut zone and are expecting the hens they're hearing to come to them. It may be worth going without calling to see if that works. Is there any way you could get out in front of them without being seen?
All I can do is wish you luck and tell you to keep after 'em. Be patient. Everything could change your next time out. Good luck (it never hurts to have good luck).
Luck Counts, good or bad