LinuxQuestions.org - Wifi device not coming up

I am new to linux and bit frustrated. I am using an embedded system running linux. My problem is my wifi device/network does not come up.

I am using WEP key and I use /etc/wifi-radar.conf and /etc/network/interface to configure (see in the bottom)

1) Sometimes (after reboot) wifi device come up but I do not see key in the iwconfig.
root@taodemo:~# iwconfig eth2
eth2 IEEE 802.11b/g ESSID:"default"
Mode:Managed Frequency:2.437 GHz Access Point: 00:14:A5:35:91:D8
Bit Rate=11 Mb/s Tx-Power=15 dBm
Retry short limit:8 RTS thr=2347 B Fragment thr=2346 B
Encryption key:off
Power Management:off
Link Quality=33/100 Signal level=-85 dBm Noise level=-96 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:30 Invalid misc:7650 Missed beacon:0

root@taodemo:~# ifconfig eth2
eth2 Link encap:Ethernet HWaddr 00:1F:7B:35:00:E7
inet6 addr: fe80::21f:7bff:fe35:e7/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:2 errors:0 dropped:0 overruns:0 frame:0
TX packets:25 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:84 (84.0 B) TX bytes:5331 (5.2 KiB)

If I go ahead and put the WEP key manually it shows up in iwconfig but still no ip address:
root@taodemo:~# iwconfig eth2 key 4072440724
root@taodemo:~# iwconfig eth2

eth2 IEEE 802.11b/g ESSID:"default"
Mode:Managed Frequency:2.437 GHz Access Point: 00:14:A5:35:91:D8
Bit Rate=11 Mb/s Tx-Power=15 dBm
Retry short limit:8 RTS thr=2347 B Fragment thr=2346 B
Encryption key:4072-4407-24 Security mode:open
Power Management:off
Link Quality=36/100 Signal level=-84 dBm Noise level=-96 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:36 Invalid misc:9180 Missed beacon:0

root@taodemo:~# ifconfig eth2
eth2 Link encap:Ethernet HWaddr 00:1F:7B:35:00:E7
inet6 addr: fe80::21f:7bff:fe35:e7/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:20 errors:0 dropped:0 overruns:0 frame:0
TX packets:25 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:840 (840.0 B) TX bytes:5331 (5.2 KiB)

root@taodemo:~
2) Sometime (after reboot) I get following error message and device does not come up:
[ 39.653869] libertas_sdio: Copyright Pierre Ossman
.
[ 39.670318] libertas_sdio mmc1:0001:1: firmware: requesting sd8686_helper.bin
[ 39.908081] libertas: failed to load helper firmware
[ 39.913513] libertas_sdio: probe of mmc1:0001:1 failed with error -110

3) Sometimes (after reboot) wifi device does not come up. I see following error:
[ 5167.019317] libertas_sdio: Copyright Pierre Ossman
[ 5167.040283] libertas_sdio mmc1:0001:1: firmware: requesting sd8686_helper.bin
[ 5167.346405] libertas_sdio mmc1:0001:1: firmware: requesting sd8686.bin
[ 5167.428741] libertas: failed to load firmware
[ 5167.444976] libertas_sdio: probe of mmc1:0001:1 failed with error -5
done.

My configuration files are as follows:
wifi-radar.conf
root@taodemo:/etc# more wifi-radar.conf
[DEFAULT]
ifup_required = False
auto_profile_order = HOME_WITHDHCP
speak_up = False
scan_timeout = 5
loglevel = 0
interface = auto_detect
commit_required = False

[HOME_WITHDHCP]
prescript =
use_wpa = no
postscript =
essid = default
use_dhcp = yes
key = 4072440724

/etc/network/interface
root@taodemo:/etc/network# more interfaces
# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8)

# The loopback interface
auto lo
iface lo inet loopback

iface wlan0 inet dhcp
wireless-essid default
wireless-key 4072440724

iface eth1 inet dhcp
# address 192.168.2.110
# netmask 255.255.255.0
# gateway 192.168.2.1
iface eth2 inet dhcp
wireless-essid default
wireless-key 4072440724
wireless-rate 11

Any help would be greatly appreciated.