I have tried to use a laptop for watching dvd on my tv. The laptop is an old HP Elitebook 2570p. For the connection I use a cable from the DisplayPort outlet of the computer to a HDMI outlet of the TV. This way I am able to project the desktop of the laptop to the tv screen, so something is working. But as soon as I start the DVD (using VLC) I get a "no signal" on the screen. Why is this, and is there something I can do?