Would you send us some good clear photos of your tree so we can evaluate what is happening.

Not sure if you got these photos....

The emerging buds on the lower branches are a good sign. I would give the tree another month to see if it recovers from our strange winter. If the upper branches are still bare you may wish to have a certified arborist make a house call to diagnose the problem. The trunk appears to be normal without damage from critters or machinery. You could possibly have some winter dieback due to lack of water in the fall. I do have some concern regarding the blackish buds on the third photo. But the emerging leaves in the center photo seem to come from areas that also were blackish. It may be that is just normal for the tree. If you do decide to contact a certified arborist later you can go to this web page and click on Find An Arborist. You can put in your zip code to narrow the search: http://www.treesaregood.org/