Wifi: got drivers but no signal

I'm running Debian Lenny on a Toshiba A200 notebook:

$ lspci | grep Wireless
03:00.0 Ethernet controller: Atheros Communications Inc. AR242x 802.11abg Wireless PCI Express Adapter (rev 01)

So I installed linux-image 2.6.32 from the Debian backports repository:

$ uname -r
2.6.32-bpo-4-686

This gives me, and loads the driver necessary for my wireless chipset.

$ lsmod | grep ath
ath5k                 103958  0 
mac80211              122310  1 ath5k
ath                     5982  1 ath5k
cfg80211               86941  3 ath5k,mac80211,ath
led_class               1757  2 ath5k,sdhci

# iwconfig
lo        no wireless extensions.
eth0      no wireless extensions.
wlan0     IEEE 802.11bg  Mode:Managed  Access Point: Not-Associated   
          Tx-Power=0 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off

and: # ifconfig wlan0 up reports success. (# echo $? returns 0)

But:

cat /proc/net/wireless
Inter-| sta-|   Quality        |   Discarded packets               | Missed | WE
 face | tus | link level noise |  nwid  crypt   frag  retry   misc | beacon | 22
 wlan0: 0000    0     0     0        0      0      0      0      0        0

So not surprisingly wicd finds no wireless networks. What have I missed? (wireless switch under notebook is on!)