Why won't my GUI hide after deselecting Visibility?

I am making a GUI which has a Show/Hide button. For some reason, this does not work. The other problem is when I try to run it in Roblox studio and change the visibility there, it does not turn off. There are no syntax errors detected by Roblox studio. This is also being used in a Seat so when you sit on it it gives you the GUI (will be placed in seat.

Here is the code:

Guithing = script.parent.parent.Frame --Only frame object there

function onClick()
	if Guithing.Visible == true then
		Guithing.Visible = false
	elseif Guithing.Visible == false then
		Guithing.Visible = true
	end
end

script.parent.MouseButton1Click:connect(onClick)

Here is the folder structure:

Seat

-StarterGui

--ScreenGui

---ControlGui

----Frame (To Hide)

-----...22 text labels...

----TextButton (Button To Hide)

Are there any errors in the output? Also I suggest replacing

function onClick()
    if Guithing.Visible == true then
        Guithing.Visible = false
    elseif Guithing.Visible == false then
        Guithing.Visible = true
    end
end

function onClick()
    Guithing.Visible = not Guithing.Visible
end

to take up less space

parent needs to be Parent

and im assuming you tried to turn visible off in the StarterGui folder

in studio, you have to go to the player in Players and find the Gui and turn it off there

Guithing = script.Parent.Parent.Frame -- you probably need to change this now 

	function sit()
    Guithing.Visible == true 
end

function off()
Guithing.Visible == false
end


script.Parent.Touched:connect(sit)
script.Parent.TouchEnded:connect(off)

or to keep it your way

local player = game.Players.PlayerAdded()
Guithing = script.Parent.Parent.Frame -- you probably need to change this now 

	function sit()
    local clone = Guithing:Clone() 
clone.Parent= player.PlayerGui:FindFirstChild(sit.Name)
clone.Visible = true
end

function off()
player.PlayerGui:FindFirstChild(sit.Name).GuiThing:Destroy()
end


game.Workspace.Seat.Touched:connect(sit)
script.Parent.Parent.Parent.Seat.TouchEnded:connect(off) -- name "Seat" what ever it is you are naming it in Workspace