Problem with using mobile as GPRS modem

I have a Nokia 5220 XpressMusic. When the phone is plugged into
the USB port of a PC runing Ubuntu, a network connection is via
GPRS is established automatically. However, that does not happen
in Mandriva. I have tried on on Mandriva 2010. Please help me
to get my mobile working with my PC running Mnadriva.

When the phone is plugged into the USB port of a PC running
Mandriva 2010.2 and the network applet is clicked, an tabbed
entry named "Wired (Ethernet) Nokia Nokia 5220 XpressMusic" on
usbpn0 is visible.

When the tab is clicked, three buttons labelled 'Monitor',
'Configure' and 'Connect' appear.

When Connect is clicked, an alert box fleetingly appears and
that's all. No connection is established. The WM session also
dies and I get logged out.

How can I go about diagnosing the problem?

$ ls -l /dev/ttyACM0
crw-rw---- 1 root dialout 166, 0 2011-03-10 14:34 /dev/ttyACM0

-C