samba - Apr 2013 - samba3.5- problem with domain member client logon

Hi all,
I installed the samba-3.5.10-125.el6.x86_64 on my CentOS 6.3.Then I add a
file share.
My client is a windows 7 machine and it join a ad.And the ad'name is
360BUYAD.LOCAL.My file server doesn't join the ad.
When I use a user that the user is also in the ad to attach the network
filesystem, then reboot the windows client,when the computer logined,the
network filesystem not logon successfully.But I use a user that the user is
not in the ad to do that,the network filesystem will logon successfully.Why
that happend?

The fllowing is my smb.conf:

[global]
workgroup = 360BUYAD
server string = Samba Server Version %v
 netbios name = vdesktop_user_server
# logs split per machine
log file = /var/log/samba/log.%m
# max 50KB per log file, then rotate
max log size = 50

security = user
passdb backend = tdbsam
load printers = yes
cups options = raw

[homes]
comment = Home Directories
browseable = no
writable = yes
valid users = %S
; valid users = MYDOMAIN\%S
[printers]
comment = All Printers
path = /var/spool/samba
browseable = no
guest ok = no
writable = no
printable = yes