[UDim2] Part Health Script Please Help? :D

So I made a script that changes a value and now I want the GUI to change Colors when it goes below a certain number :D

while true do
    wait()
    script.Parent.Text = game.Lighting.Value.Value
    if game.Lighting.Value.Value <= 10 then
        script.Parent.BackgroundColor3 = UDim2.new(221, 0, 3)
    end
end
--Output
--[Players.Player1.PlayerGui.ScreenGui.TextLabel.sc:5: attempt to index field 'BackgroundColor3' (a nil value)