What it seems like is that the RF-out is not working on your DVD recorder. When the recorder is off, the recorder should basically pass what goes into the antenna input straight to the RF-out to pass on to the TV. I had a quick look through the manual for your DVD recorder, but could not find anything on disabling/enabling its RF-out.
In the mean time, try checking the coaxial cable connection between the DVD recorder's RF-out and the TV. If the both ends are already firmly pushed in, try a different RF cable. If this does not work, then it's likely the RF-out has gone bad.
If you still have no luck, a workaround is to get a simple Y-splitter, plug it into the wall aerial socket, connect one out to your DVD recorder's RF-In and connect the other to your TV's RF-in.