PPPoE settings on HD installed knoppix

My knoppix 3.2 connects to the internet with ADSL: there is a utility for PPPoE configuration that works fine. I just provide my ID and password, and have a 24h connection.

I installed knoppix on my HD with the command: knx-hdinstall.
Everything works now *but* the ADSL/PPPoE configuration tool.
It opens a shell and then shuts it down and disappears after half of a second.
No more internet, it seems.

Why?
What can I do?
Is there a manual way to set the thing?

Thanks.
Luigi