Video won't play

I don't know about stereo installation but a customer at walmart wrote this review so it seems it worked for them. Also I have an exact unit with the only difference being that mine is sold as "DP Video, model: DP432" but everything is the same as your unit and it works fine.

"I am happy with this product and it works great. I read before I bought it that a customer was dissatisfied because it had to be in park to work, but if you ground out that wire it works fine all the time. Clear screen and its not too small like some of the others I've seen. I would definitely recommend this product."
http://www.walmart.com/catalog/product.do?product_id=6537421#ShortReviewTitleBar

Anyways, my advice is that you have it professionally installed to get it right, if you did then take it back to your installer and let them know it's not working right.

I am not sure about that brand but you are relly supposed to connect the wire coming out of the back of the screen that says "parking brake wire" to the cars parking brake wire or it can by green, black , or several other colors depending on the manufactor. If you do not do that and you just connect that wire to the ground wire "the black one" and it does not work the the screen most likely needs to have some sort of reaction to happen. try turning the unit on then grounding the black wire (the one coming from the unit that should be connected to the vehicles parking break wire) . You may have to install a switch if this works. If you still have the manual look and see if it tells you if the is a sequence like turn on the unti then apply the parking brake release it then reapply and this will tell you how to wire up the switch.