Had many UDim2 animations script fixed. But this one does still only work in Studio?

I have a lot of scripts with UDim2 animations for my Gui.

First fix is that it got changed to Local Script Second fix is that I used WaitForChild()

But this single script does still not work. (Not at all) It works completely fine in studio. It gives me no errors.

local num = 50
local backbutton = script.Parent.Parent.Back
local Image = script.Parent.Parent:WaitForChild("Island")
local Loco = script.Parent.Parent:WaitForChild("Loco")

function onClicked()
    script.Parent:TweenPosition(UDim2.new(0.9, 0, -0.9, 0), "Out", "Quad", 1)
    script.Parent.Parent.TextButton:TweenPosition(UDim2.new(-0.9, 0, 0.9, 0), "Out", "Quad", 1)
    script.Parent.Parent.Change:TweenPosition(UDim2.new(0.5, 0, 0.3, 0), "Out", "Quad", 1)
    Image:TweenPosition(UDim2.new(0.9, 0, 0.4, 0), "Out", "Quad", 1)
    Loco:TweenPosition(UDim2.new(0.42, 0, -0.9, 0), "Out", "Quad", 1)
    for i = 1, num do
        backbutton.BackgroundTransparency = 1 - i/num/2
        backbutton.TextTransparency = 1 - i/num/2
        wait()
    end
    if backbutton.BackgroundTransparency == 0.5 then
        for i = 1, num do
            backbutton.BackgroundTransparency = backbutton.BackgroundTransparency - 0.01
            backbutton.TextTransparency = backbutton.TextTransparency - 0.01
            wait()
        end
    end

    script.Parent.Parent.Back.Active = true
    wait(0.6)
end

script.Parent.MouseButton1Down:connect(onClicked)