Wireless capture

Hi,
I did wireless frame capture with wireshark, It works fine while I'm
using FreeBSD-6.
After I upgraded FreeBSD-7, I got a message:
ieee80211_load_module: load the wlan_scan_monitor module by hand for
now.

But I can not find out 'wlan_scan_monitor' module, only wlan_scan_ap and
wlan_scan_sta in /boot/kernel.

/Eric