Hello, I have one problem with airmon-ng.

When I'm typing airmon-ng
I've got something like that:

And then when I'm typing airmon-ng start wlan0
I've got something like that:

I should have (monitor mode enabled on mon0) or other
But there is just monitor mode enabled

And I can't do the next step because airodump-ng mon0 doesn't work.

My WLAN Adapter:
Realtek RTL81885

and I'm using BackTrack 5

Can someone help me? Please.