quantity cannot be reduced

Error in Ax 2012: The quantity cannot be reduced. The number of inventory transactions on order is too low because the quantity or part of it is referenced by an output order or a production order or is marked against other transactions 2

Steps to repro this error: Create SO with 20 quantities. Perform Picking List with 20 quantities Perform Picking List registration with 10 quantities Perform packing slip with 10 quantities Now, reduce the quantity @ SO line from 20 to 15. System throws the following error message;         […]