Unexpected Tran Code 70

Hi,

We have a scenario where tran code 70 is posted with a shortage adjustment. We need to understand what scenario does it depict. The scenario was like below

Day 1 Shipment Item1 3 untis ( Tran Code 30 3 units 30 cost)

Day 2 Shortage 3 units (Tran Code 22 -3units -30 cost)

Day 2 Tran Code 70 ( -3 units, some random cost)

Shortage transactions and Tran Code 70 were posted at the same timestamp which suggests that shortage  is posting tran code 70.

Before Day 1 the stock on hand of the item was Zero so the genuine scenario of tran code 70 postings when the base stock is -ve is ruled out. Any how if that is the case then the tran code 70 should be posted at the time of shipments(Tran Code 30)