Once connected, press Fn-key & F5-key (usually for laptops). You will see choices of selecting laptop screen, both or TV screen - make your choice.

If Fn and F5 are not keys for you than look key with screen signs on it among the F1 to F12 keys (ussually at the top fo your keyboard.

If this doesn't work than on you desktop (in an empty space) right click - in the menu that appers select personalize or properties. If you are using vista than on left side click on "listing you will see connect to project....." and do the need full.

Hope it works.