the only fox that every came to me after howling was a gray,its happend to me about 4 times calling at night.i find it amazing that a gray fox is so bold that he acualy thinks he can steal that rabbit away from a coyote.i once had a red bark back at me after running a coyote killing a rabbit tape.but probtrapper is right,generaly speaking if you want fox don't howl or make any coyote sounds,coyotes love to eat fox.like probtrapper said you my have done nothing wrong,were you in stealth mode going to the stands?did you keep your movment to a minamum?was your camo working for you or against you?were you sky lined?and the list goes on.pay strick attention to details when looking for stands sites and when going into hunt.but regardless of how well you set up and call sometimes nothing comes in.don't let it bother you just move on.i have on more then one occasion spent the morning or afternoon calling to what seemed like nothing.its just the way it is.