Sometimes they just don't gobble, I've had a turkey gobble once and than just shut up. Called for a little while, about a half hour after the one gobble hes standing 30 yards away.
surprised me a little but I got it. it was just a little Jake but its a good example.
One tip I can give you is to set up 20-80 yards behind your original set up to sound like the hen has lost interest and is walking away. 7 out of 10 times that works for me.
and sometimes it helps if you just move 20 yards at a time.