[Samba] Problem with Redhat 8 and access control of files

[bgforum2002 at yahoo.co.uk]

I have a RH8 and samba version 2.2.7-security-rollup-fix. The problem is 
I can't change the permissins of files from Windows clients (NT and 
2000). If I am logged as some user, create a file on some share and then 
try to change its permissions (for example trying to add read access to 
Everyone) it responds with Access denied. I have almost the same setup 
on another test machine with Gentoo Linux and Samba 2.2.8 and it works 
perfectly. I don't use posix acl,  just the default unix permissions. 
This is what the log output shows:

[2003/08/12 10:59:16, 2] smbd/open.c:open_file(245)
  user opened file RFC/rfc1.txt read=Yes write=No (numopen=2)
[2003/08/12 10:59:16, 2] smbd/posix_acls.c:set_canon_ace_list(1764)
  set_canon_ace_list: conn->vfs_ops.sys_acl_set_file type file failed 
for file R
FC/rfc1.txt (Operation not supported).
[2003/08/12 10:59:16, 2] smbd/close.c:close_normal_file(213)
 
And my smb.conf

   workgroup = Mydomain
   server string = My Server
   hosts allow = xx.xx.xx.0/255.255.255.128
   printcap name = /etc/printcap
   load printers = yes
   printing = lprng
   log file = /var/log/samba/%m.log
   max log size = 50000
   log level = 2
   security = domain
  password server = PDC BACKUPDC
   encrypt passwords = yes
   smb passwd file = /etc/samba/smbpasswd
   local master = no
   os level = 33
  dns proxy = no
  default case = lower
winbind separator = @
winbind uid = 10000-30000
winbind gid = 10000-20000
admin users = Mydomain at admin
#============================ Share Definitions 
==============================
[homes]
   comment = Home Directories
   browseable = no
   writable = yes
   path = /home/Mydomain/%U
   create mode = 0700
   directory mode = 0700
   guest ok = no

[Mydomain]
   comment = Admin Share
   writable = yes
   valid users = Mydomain at Admin @"Mydomain at Domain Supervisors"
   path = /home/BNSA
   guest ok = no

[printers]
   comment = All Printers
   path = /var/spool/samba
   browseable = no
   public = yes
   writable = no
   printable = yes

[public]
   comment = Public Stuff
   path = /home/public
   public = yes
   writable = yes
   printable = no
   guest ok = no

[docs]
   comment = Linux Docs
   path = /usr/share/doc
   public = no
;   browseable = no
   writable = no
   valid users = list of users
   printable = no
   guest ok = no
   write list = Mydomain at Admin

What could be the reason of this behaviour and how can I solve the problem?