overhead dvd player in kia borrego

  i'm having a problem wiring my dvd player to the door switch on my 2009 kia borrego.  i ran a wire to the ignition to run the dvd player.   tied in the dome light to the 12v feed from the battery (white wire).   i attached  the ground to the black wire.  when i attach the door switch wire from the dvd player to the door switch wire from the vehicle(yellow) the unit works backwards.  when the door is closed the light turns on.  when the door is open the light turns off.  for some reason the door switch wire from the vehicle recieves 12v while the doors are closed and loosing power when the doors open.  i did a continuity test on the original dome light and when the switch is turned  on to door, i get continuity from the wires i'm using for the dome light on/off button(white)  on the dvd unit and the yellow wire which i'm assuming is the door switch.  the only thing i can think of doing is splicing off the rear dome light, but i'm thinking it's probably wired the same way. 

you have to disconnect that wire from the ignition that is tied into the dome lightboxead78