Script works fine in studio but breaks in game with no error message. why?

ok this has stumped me and i have no idea how to fix it. Its supposed to be a custom loading screen i designed for my game. and it works great. i go to test it in game(not in studio) it does nothing and no error message. help?

local prog = 0

script.Parent.Parent.Parent.Parent.PlayerAudio.IntroMusic:Play()
script.Parent.Parent.Parent.Parent.Parent.CameraMinZoomDistance = 10
local player = script.Parent.Parent.Parent.Parent.Parent.Name
workspace:WaitForChild(player).Humanoid.WalkSpeed = 0


while wait() do
    prog = prog + 0.5
    script.Parent.Size = UDim2.new(prog/100, 0, 0.1, 0)
    script.Parent.Parent.LoadingLabel.Text = ("Loading...   " ..math.floor(prog*2).. "%")
    if prog == 80 then
        wait(1)
        script.Parent.Parent.LoadingLabel.Text = "Loaded!"

        local A = script.Parent.Parent.LoadingLabel:Clone()
        A.Name = "LoadedLabel"
        A.Parent = script.Parent.Parent

        script.Parent.Parent.LoadingLabel.TextTransparency = 1


        script.Parent.Parent.Parent.Start:TweenPosition(UDim2.new(0.229, 0,0.051, 0),1,7,3)
    end
end