I purchased a 2004 Honda Accord with the Concept dvd/cd player already installed. I am having problems with the sound on this device. I can put a dvd in and see the picture however there is no sound. I was told to search for sound using the radion station however that has been unsuccessful. What is the proper way to use this in order to actually hear the dvd that is playing? Also on the a/v in input could this be used to play music from an ipod/iphone?