Can't get my S-video card to work on my LCD TV?

I have a Dell 700M and it has a S-video function "FN + F8" doesn't do anything when i have the s video cord connected to the TV. Am I missing anything, like a program, software or key strokes?|||Right click on the desktop, and go to properties, then settings. Somewhere in here is going to be the setup for an external monitor, possibly in advanced