iwconfig trouble

[capacity77 at tin.it]

Hi all!
I still can't set the mode to Master, If I run

iwconfig wlan0 mode Master

I get
 
Error for wireless request "Set Mode" (8B06) :
    SET failed on device wlan0 ; Operation not supported.

I'm using a Compaq WL 100 with the linux-wlan-ng driver, kernel 2.4.26.
Anyone knows what happens? I have the wireless tools v27, do I need to use
any wireless extension?
Thanks for the help
Dom