This error is pretty self describing. It is more common in testing a system where you are making up fake data then in real life.

In real life you normally will have grabbed the physical part from the stockroom so you know it is there. As a result this likely means either that:

• In this stockroom the part goes by a different name/id.
• the stockroom needs to be updated to include this part in the computer records
• You entered the wrong part
• It used to be in this stockroom but no longer is, a count showed there were none left and it was removed from the computer records now you found one extra.