statistics always zero?

What would make link quality, signal level, and noise level statistics
always zero, even though it's working?


wlan0     IEEE 802.11-DS  ESSID:"Wireless"  Nickname:"Jeep"
          Mode:Managed  Channel:7  Access Point: 00:30:AB:16:1F:4E
          Bit Rate:11Mb/s   Tx-Power=15 dBm
          Retry limit:8   RTS thr=1536 B   Fragment thr=1536 B
          Encryption key:DEAD-BABE-BEEF-BABE-B00B-BABE-EE   Security
mode:restricted
          Power Management:off
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0