'Last used' update in aggregate

Hi

Can experts please share with me when was the value update 'Last used' in aggregate? From the SAP note, it says that date will be updated in this field. I have a cube with aggregate 'company code', 'store','department code', 'calendar yar/month' and 'calendar year' was defined.

However, I am not able to see the value on column 'Last used' when I execute the query with selection by company code, store, department code, calender year/month were filled up. Of course, there are others selection fields available as optional. In the query with the default format defined as 'calendar year/month', 'store', 'department code' follow by the key figures. I am wondering why the 'last used' not get updated in the aggregate? Or, do we trigger any job in order to update a value in aggreate?

Regards

Kang Ring