Get controlled pawn not working in real network enviroment

I have this strange problem I am trying to solve, but it seems it kinda beyond my skills. Please Help!
I am using Get Controlled Pawn in my custom player controller blueprint, It worked pretty well when I am testing on my own computer, with multiplayer( I am using 2,3,4 players and everything works fine) ok.
but when I copy the project to one of my classmate’s computer to test if the networking really works, the Get Controlled Pawn returns None.
here is my custom controller blueprint and the event is called from my custom game mode.

Is there another way to work around this one?
Thanks in Advance.