Item category for item & cannot be determined

What causes this issue?

For this item no appropriate item category could be determined.

How to fix this error?

Check the item category assignment for the relevant document type and
expand it, if necessary.
INCLUDE 'NA_CUST_MAINTAIN_3' OBJECT DOKU ID TX LANGUAGE E
IF &DEVICE&='SCREEN'
<ds:TRAN.VOV4>Proceed</>
ENDIF

Error message extract from SAP system. Copyright SAP SE.