I've got 6 swarm traps out in different locations. 4 of them never see any activity and the other 2 always seem to catch a swarm. There might not be an abundance of hives in that area you are trying. Try putting it in a different location. My 2 hives that always catch are in neighborhoods.
That's interesting that the hives in the neighborhoods catch the bees. I've noticed that my swarm trap in my yard gets no attention yet I have scout bees buzzing around me while sitting on the front porch not 100 yards away. They seem to be finicky little creatures.