Try some different sounds and different cadence! If what you're doing doesn't work, try something different!
On edit: Case in point. I talked to a guy via. internet that had finished calling a set with no shows. They were having a hard time calling anything in this one day. He had a new Fox Pro and the guy that was calling with himwanted to hear "all" the sounds that the caller had on it. They had played nearly every sound on the unit when a coyote came in!! Goes to show, if all else fails, think out side the box!!
Coyotes come for three reasons: 1)curiousity, 2)hunger, 3) territorial. You just need to trip one of those triggers!