KDM doesn't launch any WindowManager

[HuGo Herter]

Hello,
I've just installed the last version of FreeBSD (5.3), after the 
reference, but I cannot launch any WindowManager using KDM : KDM closes 
and restart immediatly...
I think that it's the same about XDM. But my Window Managers works using 
startx !

I think it's because there is no X-configuration menu during the 
installation with sysinstall... But what's the name of the new tool ?

Thanks

Hugo