So I'm camoed out up against trees using my fox pro calling on several different occasions and never see any dogs. What do I need to do?

Turn the spotlight on!

Go again!
I can't tell ya how many times I have gone out and not called anything in!
Just keep learning and make sure you take care of the basics!
Play the wind, sit still and be quiet. Approach each stand like the coyotes have their own AR and will open firs if they detect your presence! Be extra quiet leaving the vehicle and approach against the wind!
Practice makes perfect!!

Good advice thanks. A lot better than turn the spotlight on. Duh!

A lot of people are using fox pros and e calls nowadays so I'd check with neighbors and see if they are using calls because "lightning jack" is being played too often and makin em smart. Try using different sounds, also, dogs can hear pretty darn good so no need for the volume to be up so high it scares everything off.
Good luck!

JCKJR makes a great point about dogs getting smart. If you call one in you better shoot it because you probably wont see him again.

Know where they are before you start calling. They can't come if they are not there. Sneek into your calling area and be ready. Go out before daylight and make a few howls and that way you know where they are.