i have a hp laptop with nivdia geforce card. im trying to use hdmi to connect to my tv as extension/dual screen but its not working. computer is new has all the drivers and i have used hdmi cable to connect wtih ps3 so no problems there. however when i try to use it on laptop nothing happens. tv screen is black. nothing shows up on there tried mouse, draggins windows over, but nothing appears on it. anyone have any idea what i am doing wrong or why its not working??? thanks