The date for "Last access" does not seem to be updated. Why is that?
The last access date of a file is maintained by Windows. Since Windows Vista/Server 2008, Microsoft disabled the automatic update for the "Last access" date by default to improve system performance on NTFS formatteddrives. Because of this, the date won't be updated anymore if a file content is changed for example. That is also the reason why the last access date isn't a good indicator anymore for recent usage of a file.
For more information, see the MSDN homepage.