Stock Posting for Previous Period

Hi all,

In case, there is a need to update stock for previous period (Stock Transactions: Initial Quantities Stock Tracking and Stock Posting /Stock Posting List ) e.g. Update stock at 31/12/08 where there are stock movements within 2009, there is a System Message : Item quantities are not updated for initial entry of stock balances date, Update Now ?Yes , No, Cancel

How we activate this message, in case that does not appear?

Thanks in Advance