Zwets: which I use in the link room is set up for 2 way on audio and one way on video (otherwise I cannot use the DVD-1 form the main room),somehow is unable to recieve information back from the MX3500. I just says No Contact. I've tried my BL7000 on the MX3500 and this works fine.
If your Beolink 5000 is set to one-way for video it can't receive information from your MX3500. It must be set to two-way, but then you can't control your DVD1 in the main room.
Your Beolink 7000 is probably set to two-way for video.
Does the Beolink 5000 receive information from the Beosystem 4500 in the link room? If yes then there is no problem with the Beolink 5000.