You're sure you've created the mode folder in your Gamemodes folder? And also the GAME folder in the mode folder?
EDIT: By looking at
format(file,sizeof(file),GAME_FILE,GameMode)
I guess it will look for the file called: /mode/mode/GAME/GameMode (yes double /mode)
not /mode/GAME/GameMode.ini
(Although i've never scripted in pawno I think this is what is going wrong)