Breaks when I unequip?

--[Variables

tool = Instance.new("Tool")
handle = Instance.new("Part")
debounce = false

local player = game.Players.LocalPlayer
local mouse = player:GetMouse()

--[Program

tool.Name = "Codec"
tool.Parent = player.Backpack

handle.Transparency = 1
handle.Name = "Handle"
handle.Parent = tool

tool.Equipped:connect(function()
    if handle and tool then
        print("Resuming execution")
        wait()
    end
    mouse.KeyDown:connect(function(key)
        if debounce == true then return end
        debounce = true
        if key == "z" then
            print("Testing")
            wait(2)
            debounce = false
        end
    end)
end)

When I equip it for the first time and press Z, it works fine. But then when I de equip it, equip it again, and press Z, it does nothing. Anyone know why?