&-& (specify reference table AND reference field)

What causes this issue?

You must specify reference tables and reference fields for fields
containing currency amounts or quantity data. You have specified either
only the reference field or the reference table and have not maintained
either entry.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Add the missing entry. You can do this with the single field
maintenance function of the table.

Error message extract from SAP system. Copyright SAP SE.