In some cases you might need to manually over-ride a single Product inventory number.
You can manually adjust any of the fields: On Hand, On Hold, etc.
How to over-ride:
Navigate to the Product
Click on Manage in the Inventory section.
In the row for the warehouse click on Adjust Inventory
On the next screen, in the left column is a link to Override
On this screen you can now enter in the new numbers for each of the fields - enter in your desired changes and click on Save