Hi Eduard,
Are you running any 11b supported data rates like 1,2.0, 5.5, 6.0, 9.0 or 11.0
Note: The client must support the basic rate that you select or it cannot associate to the wireless device. If you select 12 Mbps or higher for the basic data rate on the 802.11g radio, 802.11b client devices cannot associate to the wireless device's 802.11g radio.
Just a thought,
Rob