You have to have a client card that supports the modulation type that is used at the 22 Mbps signalling rate, aka 802.11b+. PBCC Packet Binary Convolution Coding. If the client card does not support the modulation type, using standard 802.11b in other words, then it will not associate at 22 Mb, associating at the more common 11 Mb, using CCK, Complimentary Code Keying. Obviously the AP must also support this but I assume, based on yoru post, the SMC AP you have does.