I'm trying to create an inventory adjustment with positive and negative quantities for lot-numbered inventory items. We do not want to create a new lot. We just want to adjust the existing ones. I tried using the Issue Inventory Number field to map the lot no. related to negative quantities and Receipt Inventory Number for positive quantities. However, I still get an error such as invalid lot number reference key although I'm using internal ID.

for a negative adjustment you would need to use a Lot # already in the system.

I figured it out. I'm creating a backdated inventory adjustment for an item with a positive inventory at that time but NS compares my adjustment to the current on hand which is lower than the adjustment.

Adjust in, adjust out in separate transaction then delete first one. You will have negative inventory so be careful. Clown move, but it works.

Yup. That's what I did. Thanks for confirming. Our integration scheduled weekly hasn't taken into account the adjustment on 12/31 that I just made, so it resulted in negative inventory as of today.