[Samba] "wbinfo -n administrator" failed

[Ephi Dror]

Hi  all,
 
I have a strange situation, I hope someone can tell me what's wrong.
 
I have a samba server 3.014a joined win2003 AD.
 
When I run "wbinfo -n administrator", I am getting an error: "Could not
lookup name administrator"
 
BUT
 
If I first run "wbinfo -u" I get the list of users successfully and then
when I run "wbinfo -n administrator",  the command now  succeed.
 
Any hint what went wrong?
 
I don't see it with other domain controllers I have.
 
Thanks,
Ephi