I bought Chinese navigation from Mekede. I can't deal with connecting a factory reversing camera. There are only two connection cubes in my device. There is no third only for the camera. I measured the cables with the meter and connected in my opinion as it should be - I still do not have a picture from the camera with the reverse gear engaged. The question is, should I still connect the reverse cable from the navigation to a 12v source, e.g. rear reversing lamp?