My gamecube controller doesn’t work when im in game

Okay, so I thought to set up my old GameCube again and plug in the controllers, the first port doesn’t work but the three others work fine. I can move fine around the GameCube main menu, but when I attempted to put in super Mario sunshine, I can’t seem to press the start/pause button to start the game (but when I’m in the main menu, the start/pause button does work)

I would appreciate it if anybody could help me with my problem.