New to the forum, looking for help with a new to me 2013 GL450. I can get a DVD to play through the COMAND and through inserting a DVD into the headrest. I cannot get the DVD on the COMAND unit to transfer to the rear. I activate the rear entertainment via COMAND, on the rear unit I am only seeing "Display AUX" and " Disc drive AUX" , no COMAND options. How do I get the COMAND options to show up?