No Voltage on Reverse wire

i have a 1960 Crestliner with a 1962 Evinrude engine with the selector shifter. I have no reverse currently. I purchased a new push button gear selector and still no reverse. I started to test power across the cables and I have power across the forward ( since this one works) but no where in the wire harness does the reverse wire have any voltage. I have traced the cable from the shifter to under the console. From there it goes back to the electical box for the boat. I am unable to tell where the wire connects to inside the electrical box. Any help or suggestions would be appreciated.

Edit............ Old post.