What were you using to locate the gobblers on the roost? Not all locater calls work all the time.
I have been set up on roosted gobblers listening to hunters using calls to locate the gobblers and the gobblers never responded.
Your spot may just be a place they happen by once in a while, if your not hearing or seeing any.
Check with places near there and get permission to hunt. Try getting high on a hill and call you should hear a gobbler even way off, if you don't get one on the roost that way I would give up on your spot.