DVR Chatter

A cable technician came last week to set up a DVR for me.  He hooked up all the wires, but it wouldn't work.  He thought my RF modulator had broken because the power light was not on.  I thought he might be right because the light is usually on, so I told him to leave it and that I would get a new RF modulator.  But after he left, I was playing around with it.  When I switched to the DVD player the power light on the RF modulator came on and the DVD player worked fine.  So the problem is not with the RF modulator, but with the DVR or the way it's connected.  I've played around with it a lot, but cannot figure out how/where to connect all the wires.  The user manual does not help......  I have a Magnavox TV with only a 75 ohm antenna plug in the back.  I have a Samsung DVD-V8500 (DVD-VCR combo), and a RCA combination RF modulator and switcher.  The DVR is a Motorola DCT6412.  Before setting up the DVR, I had a cable box which worked fine with the equipment I have.......  (I think part of the problem is that my old cable box had both cable in a cable out screws, and I connected the cable box to the RF modulator that way in addition to the audio video cables.  But the DVR does not have a cable out screw.....)

Any help/advice you can give would be appreciated!