[Samba] mapping with username: "user@domain" failed

[Ephi Dror]

Hi All,
 
When trying to map my SAMBA share from WinXP, it prompted me for name
and password but it failed when I used name at domain.com
However,  using "domain\name"  worked.
 
Any idea why my SAMBA server didn't accept this name style  name at domain
?
 
Assume: Realm (AD domain): domain.com 
Pre-windows2000: domain
Username: name
 
Samba server: 3.0.7 (soon will switch to latest)
 
Am I missing something, I thought SAMBA should support it.
 
Did I miss any important  param at smb.conf ?
 
Cheers,
Ephi