If you have a -W model phone, then need to enable world mode on the AP. This is disabled by default on the Cisco autonomous APs.
Not sure if this is a config issue w/ authentication/encrytpion.
7921 currently only supports LEAP and EAP-FAST for 802.1x. Will use LEAP when in AKM mode except for when doing PSK.
Would suggest trying to get the phone associated with open and no encryption first, then can go from there.
Also ensure that no channels are disabled in the advanced network profile to ensure the phone is scanning those channels.