how to find out why networkmanager does not connect any longer?

[Rolf Schumacher <rolf august de>]

upgraded to debian sid 2.6.32-7
kde 4.3.4
network-manager 0.7.999

What I did:
I installed the package network-manager-kde, that is based on
network-manager.
I installed it on 2.6.32-6 and was happy:
I could choose from wlan ssid's surrounding me.
I could enter my 3G details and connected to two different umts networks
via two different chips: Huawei E160 and Ericsson F3507g.

Than, I upgraded to the newer kernel (and maybe some other newer libs).

What I got:

Now, I'm no longer able to connect to a ssid. If I click on an ssid the
KNetworkManager dialog closes without any message, but no connetion is
done (in the past there was a rotating gear till connection).

Also the ttyasp interface is not shown any longer in favor of usb0. And
it constantly displays "no carrier" below it where my umts supplier used
to get displayed.

Question:

What can I do to identify the mistake behind this and bring
network-manager up again as it was?


Rolf