Network manager not handling interfaces

[Githin Alapatt <githin gmail com>]

I recently upgraded from lenny to squeeze. I used to manage my
networks using the gnome applet.

In the new installation, network manager fails to show up any of my
network device. I made sure that the interfaces are not listed in
/etc/network/interface (I commented them out). Still the network
manager fails to show any device (eth0 and wlan0)

I can use eth0 by configuring it with the /etc/network/interface. That
works fine.  But, I would like to use the network manager, whenever I
need to use my laptop on an wi-fi connection.

What else could be wrong?

Thanks