Help! Don't Know What is Wrong
 

I have a Pioneer AVH-3200 in my truck and today I installed a rear view camera. Everything worked fine right after I installed. I went down to the store and when I got back in the truck and started it up, the screen was stuck on rear view mode. Sound still plays and I can control the volume and change songs but the screen is stuck on the blank rear view screen. When I put the truck in reverse the camera turns on, but when i take it out of reverse it goes back to the blank rear view screen. I have the positive and negative of camera wired to the trailer harness but I haven't ran the wire from the head unit to the reverse signal wire. Could this be what is making the screen freeze?

Thanks
Matt