Change my profile and modifier date / modifier user

Wednesday 03 February 2010 7:00:10 am

Hi,
I have this problem:
1) I logged in at admin interface, used User Account to can change my profile (for example my name or my password). I can see in the field "modified date" and "modified by user" the correct date and user.
2) I logged (user/login) in at the site and used link "my profile" to change password (/user/password/), it worked well, but in the admin interface the field "modified date" and "modified by user" doesn't change.
Same problem for the notification system to "user" node, the first point works well, the second point doesn't work...why?

My administrator needs to know when a "site user (Members)" change his profile...how can I do?

Thanks

Lisa