Why isn't this KeyDown script working?

My script resets a player when a tool is selected and "r" is pressed. The script is a LocalScript and is in a Tool.

function onKeyDown(key) 
	key:lower() 
	if key == "r" then 
		game.Players.LocalPlayer.Character.Humanoid.Health = 0
	end
end 
 
 
function onSelected(mouse) 
	mouse.KeyDown:connect(onKeyDown) 
end 

script.Parent.Selected:connect(onSelected)

But it doesn't do anything. Can anyone help me out?

I've tested this in studio, and it seems to work just fine. Perhaps you made it a Script instead of a LocalScript?