Take the DVD Recorder out of the equation, will the Camcorder record anything sent to it via Composite Video or S-Video? That is what I think you're having a problem with. That the DVD Recorder can output to those connections is a given, or you wouldn't be able to watch the DVD Recorder's output on your display.
Many Camcorders can't record from Line Input, you say yours can, but you need to be sure you know how to get it into the right mode for doing that. It's typically done through a series of menu operations, depending of course on the brand of Camcorder. If the manual says it can record from Line Input, then hopefully it also outlines the procedure for doing that. It won't just be "Turn it on, plug in the cables, and hit Record". Those Line Inputs usually are also Line Outputs, and you need to get it into Line Input Mode first. You should be able to get to the point of seeing the signal being sent to the Line Input on the viewfinder (and/or LCD screen if it has one, don't they all now?), then start the recording according to the directions.