PC to HDTV, Catalyst Control Center problem (Overscan)

PC to HDTV, Catalyst Control Center problem (Overscan)

I'm trying to get to the overscan slider in CCC but in the Desktops and Displays menu I can't right click the tv in the bottom left to bring up the configure option. If i hover the mouse over the tv it says TV, Disabled. How do i enable it? It's a Panasonic plasma hooked up to my pc using an HDMI to a Radeon HD 4870 X2