su: no directory

[llx]

hi

i've got the the problem that i can't su -l <someone> an my client machine.
   $ su -l admin
   su: no directory
i can login locally, login via ssh, su -l root without any problems. 

SERVER: FreeBSD4.8 stabel (~ 1 week ago last cvs update) runs 
NIS, NFS, DNS, FTP, SAMBA, NTP
CLIENT> FreeBSD5.1 release (rebuild kernel using KERNCONF=SMP)

i didn't had problems with have no problems with the following clients:
FreeBSD 5.0 (GENERIC), OpenBSD 3.2/3.3, Linux (Suse 8.1/8.2)

what do i miss? below you see some infos from my client machine.

cheers

$ ls -ld /
drwxr-xr-x  17 root  wheel  512 Jun 20 22:46 /
$ ls -ld /home
lrwxr-xr-x  1 root  wheel  9 Jun 20 22:46 /home -> /usr/home
$ ls -ld /usr
drwxr-xr-x  19 root  wheel  512 Jun 20 19:04 /usr
$ ls -ld /usr/home
drwxr-xr-x  11 root  wheel  512 Jun 17 11:54 /usr/home
$ ls -l /usr/home/admin
total 11
drwxrwx---  17 admin   core    1024 Jun 20 17:56 admin
$ ypcat passwd | grep admin
admin:<snip>:<snip>:<snip>:Administrator:/home/admin:/bin/sh
$ ls -l /bin/sh
-r-xr-xr-x  1 root  wheel  740848 Jun  5 03:54 /bin/sh
$ mount
/dev/ad0s2a on / (ufs, local)
devfs on /dev (devfs, local)
/dev/ad0s2e on /tmp (ufs, local, soft-updates)
/dev/ad0s2f on /usr (ufs, local, soft-updates)
/dev/ad0s2d on /var (ufs, local, soft-updates)
frigi:/home on /usr/home (nfs, nodev, nosuid)