If a dog cries and whines when left in a crate, he must be trained to deal with separation and isolation. It's normal for a dog to react like this when confined to a small space such as a crate. This happens because the dog feels anxiety from being left alone and thinks he has been abandoned by his pack, or by the owners.
According to Perfect Paws, proactive training is the solution for helping a dog get used to being alone or being left in a crate. First, leave the dog in a crate for a very short period of time, and when he starts to cry, don't go back to the crate right away. If the dog continues to cry a lot, go back to the crate, spend some time there to reassure him that you didn't leave, and then go away from the crate. If the dog starts to cry again, yell loudly, "No." When the dog has been silent in the crate for at least a few minutes, go back to the crate, and praise him. The dog learns that he is not being abandoned when he is left in the crate when the owner leaves and returns to praise him.