Why is this soo buggy?

function Thingy()
    if script.Parent.Parent.Stuff.Visible == false then
        script.Parent.Parent.Stuff.Visible = true
        wait(.01)
        script.Parent.Parent.Stuff:TweenPosition(UDim2.new(0.04, 0,0.3, 0))--{0.9, 0},{-0.1, 0} to {0.04, 0},{0.3, 0}
        script.Parent.Parent.Stuff:TweenSize(UDim2.new(0, 200, 0, 300))--{0, 1},{0, 1} to {0, 200},{0, 300}
    end
end

function Thingy2()
    if script.Parent.Parent.Stuff.Visible == true then
        script.Parent.Parent.Stuff:TweenPosition(UDim2.new(0.9, 0,-0.1, 0))
        script.Parent.Parent.Stuff:TweenSize(UDim2.new(0, 1, 0, 1))
        wait(0.5)
        script.Parent.Parent.Stuff.Visible = false
    end
end

script.Parent.MouseButton1Down:connect(Thingy)
script.Parent.MouseButton1Down:connect(Thingy2)

It just disappears when i click it again and just pops up instead of tweening in