black/white thermal imaging camera problem

Ok guys I have one of those china 7" GPS that has an Audio/Video input on it. When I connect RCA video plug to xbox or to a portable DVD player I can see the picture on the GPS screen so basically GPS becomes a 7" monitor.

Now heres my problem, only reason why I bough the GPS is so I can connect a Thermal Imaging camera to it and use it as the screen, but for some reason the GPS doesn't recognize the black/white signal from my thermal imaging camera. If I connect the same thermal imaging camera by an RCA connector to any TV, TV displays the pictures.

So why wont my GPS recognize the Black/White signal from the thermal imaging camera if it recognizes any color input (dvd player, xbox, comcast cable box..). And why would the thermal camera work on with any TV, but not with this stupid GPS?

 

can anyone offer any help on this?