How much exercise is the dog getting? If you can provide sufficient amount of mental and physical exercise it usually helps considerably. An hour walk or a half hour on the treadmill before kenneling the dog will tire it out. Are you providing something for the dog to do while it's crated? Could be the dog is bored. How many hours does it spend it the crate at a time?
Also, when you put the dog in the crate--- no goodbye's, no fuss, no talking to the dog. Kennel it, turn your back and leave without a word. When you get back home, ignore the dog especially if it's whining or barking. When it calms down or in a few minutes if it is quiet, walk over and unlock the door without talking to the dog, turn and walk away. after the dog calms down you can then call it over and give it some attention. Do not give it any attention if it's crying or barking. The way you act could be creating the stress the dog is feeling.