Wifi ok on DVD boot, fails when installed

[minesheep]

1. Pushing the button has no effect – it is always retro-illuminated, which should mean it's on
   
2. It was retro-illuminated by default when the Linux was running from the DVD anyway
   

How could it be always on, even after pushed? It should be a switch to turn wifi on and off.
Tried booting from dvd again for testing?
Tried installing directly from the boot options menu or from live session desktop?
Tried to install updates from the menu with wired connection?