KDM don't work, login failed

[LEBRETON Philippe <philippe.lebreton@cti-paysloire.cnamts.fr>]

I have install KDE2.1 from debian.kde.net on my potato, but with KDM i
can't login (and wiht kscreensaver), the message is "login failed"
On, the console it's Ok, and my keybord it's OK.
Whit XDM i have no problem.

thanks