First of all, note that check to disallow negative stocks happening are done only at point of stock issuance. It does not check on incoming stocks. With this, the following scenarios can still happen:-
1) BACK-DATED EDITS
You could have a very normal looking stock ledger, like this:
Assuming user logs in on 4-Nov, and EDITS a back-dated transaction CR-567. He increased the quantity to 22 Bottles. The system allows (because the stock balance check is on the current login-date (which is 4-Nov and the system shows available balance of 40 bottles). Note that if user had done that edit on 30-Oct (where available stock balance then was 19 bottles), the system would have blocked the edit.
The resultant Stock Ledger is now:-
Even though the net closing stock on 4-Nov is still positive, the stock costing on 30-Oct had gobe awry. This is a result of allowing a back-dated transaction to be edited and the impact of it. For better integrity of stock costing, please disallow back-dated edits for staff. If this is needed for operational reasons, remember to replenish any negative stock status and re-calibrate correctly the stock ledger.
2) INCOMING STOCK ADJUSTMENT
Refer to the original stock ledger in at the beginning of this document. Assuming user discover that product in Stock Transaction (IT-234, created on 2-Nov)was an erroneous entry. On 4-Nov, he performs a back-date adjustment to IT-234, and deletes away the item in the stock transaction. The resultant stock ledger is:-
Alternatively, someone may change the incoming SE-123 quantity, and this same impact will occur. Please note incoming stocks are not subjected to the negative stock rule, and such adjustments will suddenly create a negative stock situation.
1. IF YOU CAN BAR BACK-DATED EDITS;
Go to SYSTEM -> User Maintenance -> Security Tab -> Uncheck the right to allow user back/post-dated transactions. When this user logs in, he will be restricted to enter only current-dated transactions.
2. IF YOU CANNOT BAR BACK-DATED EDITS;
Remember you cannot sell what you do not have. Replenish each stock item that went negative on each day. If there are back-date impacts, perform a Recalculate Product Cost and repost the transactions. The Recalculation will re-arrange chronologically the stock ledger andf cost out correctly for you the item.