I facing a problem when trying crack wep could anyone help !!

my card : Intel® PRO/Wireless 3945ABG


Followed the steps :

1- airmon-ng stop wlan0 :

Interface Chopset Driver

wlan0 Intel 3945ABG iwl3945 - [phy0]


2- ifconfig wlan0 down

3- macchanger --mac XX:XX:xx:xx:xx wlan0


4-airmon-ng start wlan0


Interface Chopset Driver

wlan0 Intel 3945ABG iwl3945 - [phy0]SIOCSIFFLAGS: no such file or directory
(monitor mode enable on mon0)

5- airmon-ng wlan0:
ioctl(SIOCSIFFLAGS) failed: no such file or directory


hxxp://img705.imageshack.us/img705/8374/12212009114438.png
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sorry my English bad