Changing "Price determ." from 3 Single-/Multilevel to 2 Tr.Based

[Monika]

Hello all,
Can someone please help?
Material Ledger was launched on 01.01.2011/AC with the settings in MM03:- "Price Control" = S
- "Price determ." = 3 Single-/Multilevel
- Neg. stocks in plant
Without releasing Actual costing we not have counted "Periodic Unit Price". Business decision, we now return to the Moving Average price in field MBEW-VERPR (This Moving Average Price will be only as statistical) while remaining "Price Control" = S.
We did some tests on the TST 500:
1. Changing "Price determ." from 3 Single-/Multilevel to 2 Transaction-Based on the first day of a new period - sometimes the system takes the value of the last GR and inventory, sometimes std stock value+current std value for GR and his actual from PO.
2. In addition, our business have theoretically calculated manually MAP in the excel file and we want to enter this to the basic data of the material as the initial value of MAP - the system also calculates the next MAC strangely during the consumption or reception of the current period.
3. The introduction of the initial MAP in MM03 for the previous period - sometimes the system takes into account the previous inventory "with +" and the inventory "with -" not, sometimes the difference between the MAP. xls and std.
4. Changing "Price determ." from 3 Single-/Multilevel to 2-Based Transaction during the period - system for calculating the MAP takes the std value from the last GR from this period before the change of 3 to 2.

Why the MAC is calculated differently?
How now (during the year/period or on first day of a new period), most correctly, we can activate the MAP (only as statistical) on materials, which are movements of materials, to estimate the MAP correct i.e.:

(opening MAP from. Xls + value from the PO for current GR) / total stock qty

? What is the recommendation of SAP?

BR
Monika