Gui Mouse1Down Help?[SOLVED]

Trying to do a gui button but it says that MouseButton1Down is nil when i test it

Player = game.Players.LocalPlayer
Menu = script.Parent
Play = Menu.Parent
Customize = Menu.Customize
Loadout = Menu.Loadout
Stats = Menu.Stats
Info = Menu.Info
Backing = Menu.Backing
CGUI = Menu.CGUI

function C1()
    CGUI.Visable = true
end

function C2()
    CGUI.Visable = false
end

if MouseButton1Down:connect(Customize) then
    C1()
else
    C2()
end