Поставил debian 8.1 там уже 4 samba, домен на AD2008R2
Что я только не делал, не получается авторизоваться пользователю.

В домен ввёл ,  кажется проблема в директиве valid users = @"AD\Domain admins" тут как только не пробовал и полностью домен , и без слеша , и пользователя отдельно.

wbinfo -g

domain admins
denied rodc password replication group
cert publishers
schema admins
enterprise admins
group policy creator owners
domain users
domain computers
dnsadmins
dnsupdateproxy
dhcp users

Домен вида AD.24.RU не знаю зачем так сделали )))))

smb.conf    

[global]
    workgroup =  AD
    realm = AD.24.RU
    netbios name = 1tb
    security = ADS
    encrypt passwords = true
    dns proxy = no
    socket options = TCP_NODELAY
    log file = /var/log/samba/log.%m
    max log size = 500....
#### Reg-raboty

   domain master = no
   local master = no
   preferred master = no
   os level = 0
   domain logons = no
   wins support = no
#### PRINTERS
.
  load printers = no
   show add printer wizard = no
   printcap name = /dev/null
   disable spoolss = yes

####
..
    idmap uid = 10000 - 40000
    idmap gid = 10000 - 40000
    winbind enum groups = yes
    winbind enum users = yes
    winbind use default domain = yes
    template shell = /bin/bash
    template homedir = /var/shara/%D/%U
    winbind refresh tickets = yes
    winbind offline logon = yes
    winbind cache time = 1440

[shara]
    path = /var/shara
    read only = no
    browseable = yes
    inherit permissions = no
    admin users = @"AD\Domain admins"
    valid users =  @"AD\Domain admins"
    write list =  @"AD\Domain admins"

-----

в логах пишет

2015/09/29 19:13:40.060271,  2] ../auth/gensec/spnego.c:743(gensec_spnego_server_negTokenTarg)
  SPNEGO login failed: NT_STATUS_NO_SUCH_USER
[2015/09/29 19:13:40.100792,  1] ../source3/param/loadparm.c:3179(lp_do_parameter)
  WARNING: The "idmap uid" option is deprecated
[2015/09/29 19:13:40.100875,  1] ../source3/param/loadparm.c:3179(lp_do_parameter)
  WARNING: The "idmap gid" option is deprecated
[2015/09/29 19:13:40.101027,  2] ../source3/param/loadparm.c:3582(do_section)
  Processing section "[shara]"
[2015/09/29 19:13:40.104475,  2] ../source3/auth/auth.c:288(auth_check_ntlm_password)
  check_ntlm_password:  Authentication for user [xxx] -> [xxx] FAILED with error NT_STATUS_NO_SUCH_USER
[2015/09/29 19:13:40.104560,  2] ../auth/gensec/spnego.c:743(gensec_spnego_server_negTokenTarg)
  SPNEGO login failed: NT_STATUS_NO_SUCH_USER

---------------------------------------
xxx пользователь в группе domain admins

smbd.log  

WARNING: The "idmap uid" option is deprecated
[2015/09/29 19:13:27.322028,  1] ../source3/param/loadparm.c:3179(lp_do_parameter)
  WARNING: The "idmap gid" option is deprecated
[2015/09/29 19:13:27.322130,  2] ../source3/param/loadparm.c:3582(do_section)
  Processing section "[shara]"
[2015/09/29 19:13:27.322328,  2] ../source3/lib/interface.c:341(add_interface)
  added interface eth0 ip=192.168.0.183 bcast=192.168.0.255 netmask=255.255.255.0
[2015/09/29 19:13:27.332642,  0] ../lib/util/become_daemon.c:136(daemon_ready)
  STATUS=daemon 'smbd' finished starting up and ready to serve connectionswaiting for connections
[2015/09/29 19:14:27.372953,  2] ../source3/smbd/server.c:419(remove_child_pid)
  Could not find child 1521 -- ignoring
[2015/09/29 19:15:27.434786,  2] ../source3/smbd/server.c:419(remove_child_pid)
  Could not find child 1536 -- ignoring
[2015/09/29 19:16:26,  0] ../source3/smbd/server.c:1189(main)
  smbd version 4.1.17-Debian started.
  Copyright Andrew Tridgell and the Samba Team 1992-2013
[2015/09/29 19:16:26.197236,  0] ../lib/util/become_daemon.c:136(daemon_ready)
[2015/09/29 19:17:18,  0] ../source3/smbd/server.c:1189(main)
  smbd version 4.1.17-Debian started.