I have a TP-Link TL-WN721N usb wireless adapter installed and currently Windows 7 32 bit installed and working fine.

I downloaded BackTrack Linux 5 R3 and booted through USB. I can see wlan0 but not able to get IP address. I tried searching through iwlist wlan0 scan..I could see the essid of my wireless router but when I try to connect i get following error:

Error for wireless request "Set Encode" (8B2A).
SET failed on device wlan0; invalid argument.

My wireless router is Linksys WAG 160N. My SSID is broadcasing, 11th Channel, Security Mode is WPA2-Personal, Encryption => TKIP or AES and pre-shared key is all numerical values.

How do I connect to get the ip address.

Thanks a lot in advance.