Why is this frame coming up Nil when its being called in a Variable? [Unaswered please help]

Whenever I go to tween the frame into the players view the variable that is calling the frame is going nil in online mode...

Here's my script

local GUI = script.Parent.Parent
local GUI2 = script.Parent.Parent.Parent:FindFirstChild("LeaderBoards") -- it says leaderboard isn't a property of ScreenGui

script.Parent.MouseEnter:connect(function(Enter)
    script.Parent.Size = UDim2.new(0, 215, 0, 55)
    script.Parent.FontSize = "Size36"
end)

script.Parent.MouseLeave:connect(function(Leave)
    script.Parent.Size = UDim2.new(0, 200, 0, 50)
    script.Parent.FontSize = "Size24"
end)

script.Parent.MouseButton1Down:connect(function(click)
print(game.Players.LocalPlayer.Name..' is now being Teleported..')
GUI:TweenPosition(UDim2.new(1, 0, 1, 0), "Out", "Quad", 3)
wait(1)
GUI2:TweenPosition(UDim2.new(0, 0, 0, 0), "In", "Quad", 2)
end)