iOS Question How can I restore brightness when App goes to Background

Private Sub Application_Background
    Log("Moving to BackGround")
    Common.RestoreBrightness
    App.IdleTimerDisabled = False
    Common.InactivityTimer.Enabled = False
    Sleep(10)
    Log("Move Complete")
End Sub

Public Sub RestoreBrightness

    Dim no As NativeObject
    no.Initialize("UIScreen").RunMethod("mainScreen", Null).SetField("brightness", brightness)

End Sub