samba - Jan 2008 - minimum password age

I installed samba-3.0.28-0 PDC.

I set "maximum password age" at 90 days and  "minimum password
age" at 2
days (to do some test).

pdbedit -P "maximum password age" -C 7776000
pdbedit -P "minimum password age" -C 172800

I checked "pierluigi" account with "pdbedit -Lv pierluigi"

Password last change: gio, 10 gen 2008
Password can change: sab, 12 gen 2008
Password must change:  mer, 09 apr 2008

To simulate the change of password, I changed the date on XP pc and I did 
with the logon account "pierluigi".

I would have expected that from the day "Saturday, 12 January 2008"
until
"Monday, 07 April 2008 I could receive the message
"Password expired: n days. Do you want to change the password?

Instead this message is started only at 25 March!!!!
"Password expired: 14 days. Do you want to change the password?

The "minimum password age " is working properly?
Where is the mistake?

Thanks
Andrea