In fact, it's never worked since day 1 of Windows 7. I mean from first week of its release.
Whenever I right-click on any file and go to the file's properties, under the 'previous versions' tab, it will say "searching for previous versions" for about a minute, then it will say "there are no previous versions available". I have never got Windows 7 to show any kind of previous version of any file. Is this feature broken in Windows 7? or am I doing something wrong?