Wont CLose the gui Also "Holder" is the name of the frame this is a closing box
local Holder = script.Parent.Parent.Holder
script.Parent.MouseButton1Click:connect(function()
script.Parent.Parent.Visible = false
script.Parent.Parent.Parent.Open.Visible = true
end)

2 comments
Can I see the hierarchy of the GUI to identify it?
You never reference Holder after you define it. Like SickAtHackers said, we'll need the GUI hierarchy in the Explorer window to identify the problem.