My notebook computer uses a nVidia GeForce8 8400M GS, so it is easy for me to output to a TV or a secondary display. The utility nvidia-settings provides a quick way to output to a TV or secondary display with out editing /etc/X11/xorg.conf. My /etc/X11/xorg.conf has two profiles that use for different setups. One for home and other for mobile use, so it is complicated.
It seems to me you are using an Intel or ATI graphics which will give you problems. Utility xrandr may have to be run as root.
How come I am still looking at my laptop screen??
Maybe you only have two eyes, so you need four eyes. ::p
Have not oil the neck in order to turn it to see the TV.
Seriously, you may not be on the correct input for the TV.
From the information that you gave. Your question will not be answer effectively.