Problem with display healthbar and playername above player

i have a big problem:

for some reasons, i can see the name above my friend's player... but he can't see mine.

and the second problem, is about the health bar lable (that above the player too), i can

see my friend's healthbar lable that should be above his name, but he can't see mine....

WHY THAT HAPPEN

picture example: http://imageshack.us/photo/my-images/109/problemwk.png/