TV can't retrieve signal from DVD

Hi

I have a Sanyo DVR-DX600 DVD recorder and a 50" Samsung Plasma. My DVD player has been working fine on the TV for the past 6mths up to now. What happens is when I turn on my TV and DVD, I switch from HDMI to AV on the TV, no signal is being received from the DVD on the TV. I swapped the composite cables with a different set, and still no signal, so I don't know what else to do. But when the DVD is turned on, everything seems to be working, it can read a DVD inside and it can change channels and I can see all this on the LCD display on the DVD that this seems to working fine. Only problem is howcome all of a sudden my TV can't get the DVD signal? It has been working fine the past 6mths up to now. The DVD I have owned for 1YR6MTHS and the TV 6mths.Let me know what can be solved.