Fedora directory users - Dec 2006 - help about RedHat Directory Server

I need help about how to users in Redhat Directory Server.

1. First to Add on a system with a command line [useradd]    and then add in
RDS
2.  First add in RDS and then with useradd because i am getting this error.

[root@station4 ~]# su - ali
id: cannot find name for group ID 501
[ali@station4 ~]$


where station4 is client , and home directory of RDS server is mounted here.
and that user is added in server.

So why i am getting this error, kindly waiting for a fast reply.

Regards
Linux Kid