[Samba] cannot share directories other than on root mount?

[Paul]

I have been using SAMBA for a number of years and recently switched from
slackware to FC6 which is running 3.0.23c-2. Since the switch I have
been unable to share directories that are not on the root drive.  For
example I can create a directory /mnt/backup and share it, but if I
mount /mnt/backup to a ext3 disk, then the share no longer works.  This
is a problem as my /home directory is on a second drive (ext3).

smb.conf has the share defined as...
[global] 
	workgroup = DOGPACK
	server string = Samba Server
	username map = /etc/samba/smbusers
	log file = /var/log/samba/%m.log
	max log size = 50
	preferred master = Yes
	dns proxy = No
	cups options = raw

[tmp]
   comment = Temporary file space
   path = /mnt/backup


# mount
/dev/sda1 on /mnt/backup type ext3 (rw)

#ls -l /mnt
total 12
drwxr-xr-x 9 root root 4096 Nov 29 20:17 backup


#mount -t cifs -o
username=paul,password=mypasswd //192.168.1.3/tmp/ /mnt/test1
retrying with upper case share name
mount error 6 = No such device or address
Refer to the mount.cifs(8) manual page (e.g.man mount.cifs)

#umount /mnt/backup
#ls -l /mnt
total 8
drwxr-xr-x 2 root root 4096 Nov 20 19:54 backup

#mount -t cifs -o
username=paul,password=mypasswd //192.168.1.3/tmp/ /mnt/test1

mounts ok


The Samba logs show on the first failed attempt:
[2006/11/29 21:49:31, 0] smbd/service.c:make_connection_snum(911)
  '/mnt/backup' does not exist or permission denied when connecting to
[tmp] Error was Permission denied 


I suspect this problem is also preventing me from sharing the home dirs
on /home (mounted as /hdb1 ext3)


This configuration was working on my slackware server.  I have a smbuser
and smbpasswd file with 'paul' in it.

Paul
paul at golborne.com