Did you hit the two you shot at during deer season? Shot placement on a coyote is a little different than on deer and other game most pursue. This website is an interesting read.
http://www.predatormastersforums.com/ubbthreads/showflat.php?Cat=0&Number=53011853&an=0&am p;page=0#53011853
If you're calling make sure you pay attention to wind direction. A coyote coming into a call usually will attempt to get down wind. Try to have open shooting down wind so you're able to shoot before they hit your sent line. They're one of the most difficult animals to hunt, don't give up because once you have one run into your call you're going to be hooked! Good luck, keep us posted on your first attempts and success!