Wifi dongle help

[Beans.Jb]

Code:

root@xbian:/home/xbian# ifdown wlan0
ifdown: interface wlan0 not configured
root@xbian:/home/xbian# ifup wlan0
wpa_supplicant: /sbin/wpa_supplicant daemon failed to start
run-parts: /etc/network/if-pre-up.d/wpasupplicant exited with return code 1
Internet Systems Consortium DHCP Client 4.2.2
Copyright 2004-2011 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/wlan0/d8:eb:97:18:da:eb
Sending on   LPF/wlan0/d8:eb:97:18:da:eb
Sending on   Socket/fallback
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 15
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 15
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 15
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 8
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 1
No DHCPOFFERS received.
Unable to obtain a lease on first try.  Exiting.
Failed to bring up wlan0.