AD(microsoft) + linux

ola pessoal ... mais um problemao para voces ... e o seguinte estou tentando fazer um join do meu linux num dominio nt microsoft e estou encontrando problemas( ja na fase choro), seguinte configurei meu samba :

vi /etc/smb.conf

[global]
workgroup = dirpoa01
netbios name = 2nv_05
server string = "Samba 3.0.21a w/ ADS Support"
log level = 5
log file = /var/log/samba/LOG.%m
max log size = 1024
domain master = no
ldap ssl = no
security = ads
realm = dirpoa01
encrypt passwords = yes
idmap uid = 10000-20000
idmap gid = 10000-20000
#bind interfae only = yes
winbind separator = /
winbind enum users = yes
winbind enum groups = yes
winbind use default domain = yes

vi /etc/nsswitch

passwd: campat winbind
group: campat winbind

vi /etc/krb5.conf

[libdefaults]
ticket_lifetime = 24000
default_realm = DIRPOA01
dns_lookup_realm = false
dns_lookup_kdc = false
clockskew = 300
kdc_timesync = 1

[realms]
DIRPOA01 = {
kdc = 172.16.128.11
default_domain = DIRPOA01
admin_server = 172.16.128.11
}
DIRPOA01 = {
kdc = 172.16.128.11

}

quando testo o kerberos td blz,
# kinit user@domain

mas quando tento fazer um join

2nv_srv:/etc # net ads join dirpoa01 -U Administrator
Administrator's password:
[2006/07/11 18:22:45, 0] libads/kerberos.c:ads_kinit_password(146)
kerberos_kinit_password Administrator@DIRPOA01 failed: Preauthentication failed
[2006/07/11 18:22:45, 0] utils/net_ads.c:ads_startup(191)
ads_connect: Preauthentication failed
2nv_srv:/etc #