Hi,
It seems that u must have checked the cables (S-Video) connected on both TV and TV-Out from the video card.
Make sure the TV is first on the S-Video connection, same like your DVD connection. And then right click on the desktop and detect. But dont be in the serttings tab waiting for it to detect TV. first make sure the TV is on S-Video and then right click on desktop-settings-device control, you'll get it? I got tricked myself at first