[Samba] passdb.tdb not updated when changing passwords

[Gianluca Cecchi]

I'm using samba on CentOS 3.7 (3.0.9 + rh patches)
I had smbpasswd as backend and I'm testing migration to tdbsam.
After exporting successfully to tdbsam and setting
passdb backend = tdbsam
in smb.conf
if I change from inside a windows xp machine the password ot the user and then
pdbedit-Lv user
I get
Logon time:           0
Logoff time:          ven, 13 dic 1901 21:45:51 GMT
Kickoff time:         ven, 13 dic 1901 21:45:51 GMT
Password last set:    gio, 17 ago 2006 14:59:18 GMT
Password can change:  ven, 18 ago 2006 14:59:18 GMT
Password must change: lun, 16 ott 2006 14:59:18 GMT
Last bad password   : 0
Bad password count  : 0
Logon hours         : FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

Questions:
1) it seems passdb.tdb is read but not written based on its timestamp
Shouldn't it be modified with the new encrypted password? the same
happens if for example I change full name of a user...
Where are otherwise written these informations

2) in the example above, the user cannot change today his password.
What can I do to reset this for the user?

3) It seems that no --pwd-must-change-time option is working in my environment.
Was this a late introducted feature?

4) Does it exist for latest releases also the opportunity to change
the "Password can change" date? something like --pwd-can-change-time
option?

Thanks in advance for your help
Gianluca

PS: please tell me if any question regarding customized version of
samba, such as RH, is automatically ignored by the gurus... this would
be in some way acceptable but knowing it would at least save time for
me.