I am using Ubuntu 12.04.

when I do sudo rkill list all, I get :

0 phy0 : wireless LAN (soft and hard blocked : no)

1 brcmwl-0 : wireless LAN (soft and hard blocked : no)

2 dell-wifi : wireless LAN( both soft and hard blocked : YES)

3 dell-bluetooth : Bluetooth( both soft and hard blocked : YES)

Now I want to enable only dell-WiFi on, and want to keep dell-Bluetooth blocked.

I tried :

sudo rfkill unblock dell-wifi

sudo rfkill unblock wifi

None of the above has any effect.
I even restarted my laptop but still no effect.

EDIT : even when i tried sudo rfkill unblock all, but it didn't work..!

How should i do the same??