dual/rosen match

guys hi.

I have installed a dual dvdx 9131 all in one navigation single din fold out screen head unit on my 95 land rover classic county lwb... this vehicle had an existing rosen a7 roof mounted dvd player wired to the fm modulator. I changed all that and hard wired both systems together.. my problem is. when I play a dvd on the rosen rear unit  I can tap the a/v icon on the dual head unit and watch up front, but what ever I play up front I cannot watch in the rear unit even thuo I sellect "aux input" it is as if the head unit did not give an output signal.

my wife likes to be on top of the kids when traveling specially when watching pg movies so she has mentioned wanting the ability of having control from the front seat.  how can I achieve sending video signal from front to back?

thanks for your response..

thanks I really have not had much time to play with it, the little shop time I have had with it has been dedicated to the installation or fine tunning of  the aftermarket alarm start and keyless entry (whole different issue which I posted on the security section, I think I narrowed it down to the alarm type thou). I will go over the whole install again to make sure I did not miss anything but i think it is my head unit which does not have an auxiliary out put only an input... thanks again.