Ubuntu Networking :: Atheros AR5007 Failed To Enable Wireless

Ubuntu recognize my wifi adapter which is Atheros AR5007, but when i open context menu to connect to wireless network it just simply shows me that wireless is disabled and even when i checked "Enable wireless" option nothing happened. Here is information from terminal:

Code:
$ ifconfig .....
There is no any wireless device, only my wired network.

Code:
$ iwconfig
lo no wireless extensions.
eth0 no wireless extensions.
wlan0 IEEE 802.11bg ESSID:off/any
Mode:Managed Access Point: Not-Associated Tx-Power=off
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:off
Wlan0 exists but Power Management is off.

Code:
$ iwlist wlan0 scan
wlan0 Failed to read scan data : Network is down

Code:
$ sudo iwconfig wlan0 power on

Error for wireless request "Set Power Management" (8B2C) :
SET failed on device wlan0 ; Operation not supported.
Also I tried to install windows drivers with ndiswrapper but no any luck.

My system is up-to-date Ubuntu 11.04
Code:
$ uname -a
Linux linux 2.6.38-10-generic #46-Ubuntu SMP Tue Jun 28 15:05:41 UTC 2011 i686 athlon i386 GNU/Linux