Continuing the hijack (sorry)..
True story..I am almost got hit jogging about two weeks ago by a Prius or Hybrid vehicle. I live on the outskirts of Denver..and there is some landscaping along the roads that can block the view. I listen and look for cars..did not see or 'hear' one..dashed across the road and luckily the driver hit the brakes..or my loved ones would have a modified 2002 Camaro as part of their estate.
They are kinda quiet....
Forcefed..sorry again about the HJ..
I would try Joecar's suggestion. I had a similar experience once..I had my +/- reversed..its a guess, but with Spark very few Tables add..
Good luck..