Problems using usb wireless adapter

[fake fake]

I've just got FreeBSD 9.0-RELEASE on HP Pavillion dv4.
When I found the internal wireless adapter (Broadcom BCM4322) is not
supported, I decided to use the usb wireless adapter (Planex
GW-USMicroN) which is listed on

http://www.freebsd.org/releases/9.0R/hardware.html

then I configed the several files.
(I use WEP to connect to the internet.)

/boot/loader.conf
if_run_load="YES"
runfw_load="YES"
wlan_wep_load="YES"

/etc/rc.conf
wlans_run0="wlan0"
ifconfig_wlan0="DHCP WPA"

/etc/wpa_supplicant.conf
network={
  ssid="my_ap's_ssid"
  key_mgmt=NONE
  wep_key1=my_password
  wep_tx_keyidx=1
}

but, I cannot connect to the internet.
How to solve this situation?