What is wrong with this script in StarterGUI, it is not closing when button is clicked?

function KeyPressed(Key)
if Key == "c" then
mh.Visible = false
end
end

function KeyUnPressed(Key)
if Key == "o" then
mh.Visible = true
end
end



Mouse.KeyDown:connect(KeyPressed)
Mouse.KeyUp:connect(KeyUnPressed)

It's in StarterGUI, StarterGUI>Frame>Frame>TextLabel>ThisScript So I don't know whats wrong... There's no error coming out from Console