Rear camera not recording

Make sure all wires are connected properly specifically the rear cable and the USB cable. 
When connecting the cables, make sure they are inserted all the way. If there is a gap (as image below) then it is not completely connected
It is properly connected when there is no gap between the cables as below image:
Also note that there are arrows on each end of the cables - that is the indicator of which way the cables should go in. They'll need to be aligned and connected as below image: