error 010: invalid function or declaration

C:\Users\😕\Desktop\bi-rp.pwn(35481) : warning 209: function "S@@_OnPlayerKeyStateChange" should return a value
C:\Users\😕\Desktop\bi-rp.pwn(35483) : error 010: invalid function or declaration
C:\Users\😕\Desktop\bi-rp.pwn(35485) : error 010: invalid function or declaration
C:\Users\😕\Desktop\bi-rp.pwn(35496) : error 010: invalid function or declaration
Pawn compiler 3.2.3664 Copyright (c) 1997-2006, ITB CompuPhase

3 Errors.

HELP NEKO PLS??