Exactly..I too have the same problem.
I'm using BT 4 Pre-Final (HDD Install) on my laptop in my home network. I connected to the AP using my D-Link DWA 110 (Ralink 2573 Chipset using RT73USB driver) and monitor using my Centrino 3945 a/b/g card. I can easily capture the WPA Handshake by aireplay deauth. But aircrack-ng can't crack the KEY even if i'm providing the correct key in the dictionary file. It just says "Passphrase not in dictionary"
Where's m i doing wrong?