It could be for multiple reasons. The 1st 2 that come to mind is that your source material was in a format that your dvd player is unable to play; ie: ntsc/pal/secam
Some dvd players don't play cd-r's/rw's. Or some don't like some brands of cd. Or you've burnt them too fast. Video is a highly sensitive format. Much more sensitive than audio. Try burning your cd-rw's at the MINIMUM SPEED. I've had this issue before. I reburnt them again & they played fine. I don't understand that point.