How to connect a disconnected event again?

using = true
local nafa = script.Parent.Changed:Connect(function()
	if using == false then
		print("No")
	end		
end)
script.Parent.Changed:Connect(function()
	if using == true then
		nafa:Disconnect()
	else
		nafa:Connect()
	end
end)

This is the code which doesn't even work. I want the disconnected event works again. Any help?