Authentication fails when using BackTrack 5 under VirtualBox, on Airport Express

Question

I've got BackTrack 5 running in VirtualBox on my Mac. The airport is recognized by VirtualBox as a bridged connection. BackTrack 5 is picking up the airport, and is displaying available wireless networks, so I know I'm quite close. However, upon authentication (WPA1/2), I get a bad password notification. Since the password is correct, I'm guessing it has something to do with the Macbook also being connected.

My ideas:

1. Disconnect macbook from network so both the airport card and the router aren't confused. (This didn't work, same issue of bad auth.)
2. Forward the internet connection from the mac. (Not preferable since I'll be using BackTrack 5 for penetration testing, so I need control of the card.)

Can anyone explain what's going on? I feel very frustrated to have gotten here only to be stopped by a password!