We have an asset for which some more dep (special dep) should have posted in 2008? Option 1 is to post an unplanned dep now. Doing this we will make up for 2008 but we will not get the values correctly for 2009. To get the correct values for 2009, we can post a write-up of amount ( Amt should have been posted in 2008(incl of special dep) - Amt already posted in 2008). But our period control calculates dep at mid year (07/07...). If we change the period control to (01/01..) now, we get the desired ODep for 2009. But if we dont, we get some different value. Can somebody explain why and as to what is happening by posting the write-up now with period control (07/07..at mid year)?