HDMI laptop to TV

Trying to connect Dell latitude laptop running Windows 7 pro to Panasonic 40" flat screen with hdmi cable. Computer configured to mirror 1st monitor (attached to unit) to 2nd monitor. TV input set to HDMI 1 where cord is attached. Have gone thru all the suggestions I find on Google and Microsoft. Cord is 15 ft so I can sit in lazy-boy and surf.