In a small skillet, saute celery and onion in butter until tender. In a large bowl, dissolve bouillon in boiling water. Stir in the stuffing cubes, carrot, orange juice, zest and the celery mixture., Spoon into a greased 13x9-in. baking dish. Cover and bake at 350degrees for 20 minutes. Uncover; bake 15 minutes longer or until heated through.