Some dogs develop separation anxiety.
Leave the dog in the crate for short periods of time to teach the pet that you WILL return to release it. Continue to extend the length of periods until you can leave the pet alone for several hours. Vary the time of your return, so the pet will not expect you to be there at an exact time. Teach your pet to stay in a kennel or run in the yard by moving the crate outside, leaving the crate door open. Once again, leave the pet alone for short periods of time to adjust to its new environment.