Maybe your puppy doesn't like to be alone and in small places. Puppies are hyper and they love to be with people.

When I use to sleepover my friends house, they would lock their dog up in a cage for thenight. The dog would cry, howl and bark. You could also hear him run around in circles in the cage. When she would let her dog out he would be a little angel

Maybe you should stop locking your puppy in the cage. If you are taking your other dogs on a walk, why not take your puppy along. He will sure enjoy it! Or you could take puppy to obedience classes to work on behiavor and hyperness.

Good luck!!!