how to operate satnav/dvd on honda cr-v 2004?

Just bought 2004 CR-V, anmd the DVD manual seeem to bear no relationship to the kit inside. I'm baffled how you would have the satnav running at the same time as the kids watching a dvd. Surely the main oprupose is so that on a long journey you follow the satnav and the kids are kept quiet by watching a dvd. We didn't buy from a hondas dealer, so little point going back.
The screen drops down to reveal the DVD slot and a CD slot, put DVDs in both and nothing. Says no DVD!
Any help?