Production Order changes start date

Hello Guru,

I have some question, i have created a production order with quantity 10,300 cases and with start date 18.09.2008 with 00:00 time and finish date 18.09.2008 with 07:57 time and released the order and partially confirmed with 300 cases.

After doing the partial confirmation i do change the production order quantity to 10,100 cases. and save. after this change in PO quantity, when i display the PO now start date 18.09.2008 with 07:57 time and finish date 18.09.2008 with 14:41 time.

why thus this happe the date/time thus change?

how could we find a solution that if an order and released and is partial confirmed, and been change be prevent the start date and time from changing? please help.

Thanks

Ryan