I don't know if this would pertain to your situation but if the tree's foliage is too dense and there is no area for air to circulate and light cant penetrate to the inner branches or the inside of the the tree, that will cause the inner branches to die back and or prevent inner branch development. This can also occur on outer branches if the tree is kept in the same location and not periodically turned as only one side will receive light causing flush growth on one side and die back on another.
Other than that I don't think you will receive a more appropriate answer due to lack of important information such as where the tree is located, soil/root situation,watering tactics etc..