Why isn't my camera moving when I move the mouse?

I have this problem where when I do

UserInputService.MouseBehavior = Enum.MouseBehavior.LockCenter

in my tool, the mouse doesn’t move the camera.

When I use the script above in my “Button2Down function” for my tool it works but when I use the script in my “string.lower” for my Key function the mouse doesn’t move my camera it just makes my mouse unusable, for example, when you set your Walkspeed to 0 the player can’t walk anyway with the keyboard keys, it’s kind of like that except for the mouse