If that doesn't work, I have a tip for you.
When I put mine in, the directions were very confusing. There was one part where i had to go into Display on Control Panel, go to Settings tab, and right click on the screen of the video card. Then select properties and change some stuff around to make sure my computer accepted it or something (i really dont know why i just did it). It took me 2 days to figure out what I had skipped in the directions and that was it. It also said it was optional so maybe you dont need it.
But, if nothing else works, give that a shot.