Why does this TweenPosition script work when I run a Server, but not when I play?[FIXED]

I wrote a TweenPosition script to open a Gui. It works perfectly fine when I start a Server on Studio, but when I disconnect from Studio and just play the game, it doesn't work at all. It's not giving me anything in the F9 console either. Help? It's in a regular Script, here's the code.

StatsBG = script.Parent.Parent.Parent.StatsBG
function open()
    if StatsBG.Visible == false then
        StatsBG.Visible = true
        StatsBG.Position = UDim2.new(0,545,0,-400)
        StatsBG:TweenPosition(UDim2.new(0,545,0,60), "In", "Quart", 1)
    else
        StatsBG.Visible = true
    end
end

script.Parent.MouseButton1Down:connect(open)