Why does an account segment not derive the value configured in the mapping set?

Summary:

Why does an account segment not derive the value configured in the mapping set that have like source the Inventory Category Code?

I have a mapping set configured with the source of "Inventory Category Code", so that I derive a segment of the accounting combination, the categories I am using are from a catalog that is not assigned to any functional area because it has a hierarchy, therefore I am placing the category in the first hierarchy, because several articles group this category. When accounting for the items, I am not deriving the value of the segment. What can be the cause?