SSO and Kerberos not working with AFP

I have my Leopard Server running. Everything seems to work fine. I have my clients (10.4.11) running with network home folders. If I do something like sudo klist -k | grep afpserver I get the answer that kerberos have tickets for that 3 afpserver/LKDC:SHA1.BA5B742F476AE79129075CCDBB2E4D40D91F82A7@LKDC:SHA1.BA5B742F476AE79129075CCDBB2E4D40D91F82A7 3 afpserver/LKDC:SHA1.BA5B742F476AE79129075CCDBB2E4D40D91F82A7@LKDC:SHA1.BA5B742F476AE79129075CCDBB2E4D40D91F82A7 3 afpserver/LKDC:SHA1.BA5B742F476AE79129075CCDBB2E4D40D91F82A7@LKDC:SHA1.BA5B742F476AE79129075CCDBB2E4D40D91F82A7 3 afpserver/server.asam.private@SERVER.ASAM.PRIVATE 3 afpserver/server.asam.private@SERVER.ASAM.PRIVATE 3 afpserver/server.asam.private@SERVER.ASAM.PRIVATE But now my problem. I try to enable kerberos authentification as the only possibility on AFP service and then the clients log in as guests without getting a ticket. How to enable them to get a kerberos ticket? If I enable other authentification on AFP service, it works fine and I can get tickets for example if I launch Mail and it asks for my kerberos password.