Samba4::Adding domain user with blank password?

[Andrew Shinkarchuck]

Hi there!
i have samba4.0.0alpha14-GIT-56290d0 at debian5 and 2003 server domain
controller setupped like in Samba4/HOWTO. also i have test winxp computer
succesfully joined to this domain.
i have logged on as domain administrator and tried to add user into domain
with WinServSP2 Administration Toolkit Pack "AD users and computers" tool.
i tried to add user "student" with no password but receieved error
messagebox
------------------------------------------------------------------------------
|Active Directory                                                      |
------------------------------------------------------------------------------
|Windows cant change password for student because:|
| A device attached to the system is not functioning   |
-------------------------------------------------------------------------------

Can someone explain me, why blank password are not allowed in curent samba4
version?

Thanks!