I don't know about your unit, but in mine the dvd player has just one video cable to the tv, it have to be connected in the "green" input, if there's not a yellow video input on the tv. The 3 color red, green and blue is for hd/720 res. and some of the campers dvd players do not come with that. Mine didn't! Some units are hdmi ready, I'm guessing that yours did not come with the hdmi.
(And the sound is only through the radio speakers not the tv, you'll need another audio cable for that)
hope this help!