Item Availability for Reservation with WMS and manufacturing

Hi All,

This is my first post here. I have a question for Item Reservation. The NAV is 2009 R2 NA version. Let’s say I use WMS with Location configuration as belows:
Location Code = White
Bin Mandatory = True
Directed Put-away and Pick = True

Assume I have an item with Inventory at White warehouse=100, it is already put-away. This item is salable and will be used as component in Production BOM with flushing method=Pick+Forward. “Reserve” option in Item Card is “Always”. I have created a sales order for this item with qty=60, reserved 60 from Item Ledger Entry. Then I create Pick for a released Production Order which will consume the item with qty=50. When I check the item availability now, it shows -10. I traced the NAV program, the calculation is like [AvailQty :=Item.Inventory - PickQty - QtyOnOutboundBins -Item.“Reserved Qty. on Inventory” + QtyReservedOnPickShip].

My question is : how can I prevent the reserved item from other usage except its own Sales Shipment? Since I reserved 60 from I.L.E., the available qty should be 40. And how can i prevent system create Production Order pick for more than 40? Pls help…