the owner before me had done a cowboy job of the rear light registration plate unit, so I got a new one today (scrappies), a took the wires back and put the black to black and blue to blue, but it is not working, I did notice when I took the old one off it sparked so a checked the fuses (passenger side dash board) and they all seemed to be fine, what is causing this not to work? as it was working before but as a said it was a cow boy job all taped up and looked a mess, help would be much appreciated.