I tried to get the camera to follow the player with this.cameras.startFollow(this.player) but it still did not work. it just shows a black screen, why is this?

I was expecting it to follow the player but it was not for some reason. I also tried to
camera = this.cameras.main; camera.startFollow(player); camera.setFollowOffset(-300, 225); camera.setLerp(0,0);
but it did not work. All of the things I tried ended up making the screen black.