Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
The instructions that you sent front the Apple web site (link)

It's like the card isn't going all of the way in, and the antenna will not reach it.
 
Don't be afraid to push on it. It "snaps" into place and takes a bit of force. The first time I installed one I thought it was broke because it wasn't showing up in ASP, but it turns out that it just wasn't pushed in all the way.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.