first off....welcome aboard. are you a member?
couple idea's for ya...
~scout your properties to see exactly how much sign of predators there actually is. if they are not in that particular piece of property...you obviously won't call anything in. a good place to look for scat is at road and trail intersections or at the crests of small hills/rises.
~keep your calling volume low for the first couple series and increase your volume as you call.
~don't call too much....one 30 second series every 4-5mins is enough to let anything within earshot know your there.
~most importantly watch your wind...have it either at your back or coming crossways. i prefer it coming from right to left as i'm right handed allowing me to swing downwind on a circling fox or coyote.
keep at it and don't give up...it'll come together for ya.

~Woody