[mythtv-users] How should I configure channels ?

[Pivert]

Hi !

I'm new to mythtv, and now... I'm blocked.
The actual status :
My BT878 card is well configured, and KdeTV can scan and detect all channels
distributed by my cable operator.
I'm in Belgium, ant there is no belgium choice for xmltv, so I configured 
xmltv with the command line to create the tv_grab_fr.conf that list all 
channels I can get here in Belgium from my cable operator.
MythTV is up and running.
When I run mythfilldatabase it fetches all my TV programs.

But when I try to watch TV, I have a huge amount of lines like this :
2005-09-18 19:01:17.694 Channel(/dev/v4l/video0): CheckChannel failed. Please 
verify channel "S02" in the "setup" Channel Editor.
2005-09-18 19:01:17.694 Channel(/dev/v4l/video0): CheckChannel failed. Please 
verify channel "S01" in the "setup" Channel Editor.
2005-09-18 19:01:17.695 Channel(/dev/v4l/video0): CheckChannel failed. Please 
verify channel "E4" in the "setup" Channel Editor.
2005-09-18 19:01:17.696 Channel(/dev/v4l/video0): CheckChannel failed. Please 
verify channel "E3" in the "setup" Channel Editor.
2005-09-18 19:01:17.697 Channel(/dev/v4l/video0): CheckChannel failed. Please 
verify channel "E2" in the "setup" Channel Editor.
2005-09-18 19:01:17.699 Channel(/dev/v4l/video0): CheckChannel failed. Please 
verify channel "69" in the "setup" Channel Editor.
2005-09-18 19:01:17.699 Error, couldn't find any available channels.
2005-09-18 19:01:17.699 Your database is most likely setup incorrectly.

What's wrong ?
How can I launch MythTV to scan all frequencies as KdeTV does ?
Can I reuse the export created by KdeTV (with frequencies and channel name) ?
How can I then associate channels on my tvcard with channels that are fetched. 
by xmltv ?

Thanks !