This works in Studio, but says "Frame is not a valid member of ScreenGui"?

I have this script here, it works in studio perfectly fine.

play = script.Parent.loadingFrame.playButton
about = script.Parent.loadingFrame.aboutButton
frame = script.Parent.loadingFrame
aframe = script.Parent.aboutFrame
mB = aframe.madeBy

play.MouseEnter:connect(function()
    play:TweenSizeAndPosition(UDim2.new(0,210,0,65), UDim2.new(0,15,0,200), "In", "Quad", 1)
end)
play.MouseLeave:connect(function()
    play:TweenSizeAndPosition(UDim2.new(0,200,0,50), UDim2.new(0,15,0,200), "In", "Quad", 1)
end)

about.MouseEnter:connect(function()
    about:TweenSizeAndPosition(UDim2.new(0,210,0,65), UDim2.new(0,15,0,400), "In", "Quad", 1)
end)
about.MouseLeave:connect(function()
    about:TweenSizeAndPosition(UDim2.new(0,200,0,50), UDim2.new(0,15,0,400), "In", "Quad", 1)
end)

play.MouseButton1Down:connect(function()
    frame.Visible = false
end)
about.MouseButton1Down:connect(function()
    aframe:TweenPosition(UDim2.new(.5,-250,.5,-250), "Out", "Back", 2)
    wait(1.5)
    mB:TweenSize(UDim2.new(1,0,0,50), "Out", 1)
    mB.Text = "Made by; SimplyRekt and hurtioioio101"
end)

But in a server, it says "aboutFrame is not a valid member of ScreenGui". Hierarchy here; http://i.imgur.com/qlQ9zLF.png