Depending on the laptop, even after it detects the new video output option (your TV), you need to (for Windows based laptop) right click on the desktop somewhere and click PROPERTIES. Go to the SETTINGS tab, and you should see 2 (or more) boxes in the top part of the window. Box 1 is your laptop display, and box 2 represents your possible TV output. Click once on the box 2, and then look for a checkbox on the Display Properties window that says something like "Extend my Windows desktop onto this monitor." It the TV goes all grey, or blue (can't remember if it is just your background color), then you can drag and drop application windows from your laptop screen to the TV screen by dragging them to the right of your laptop screen and if you keep going right, they will start to show up on your TV.
Not the best option always, but I had a laptop that I had to do this with in order to get it to work.
