Key fields for use data &1 and checkbox structure &2 are different

What causes this issue?

The key fields in use data structure &V1& and checkbox structure &V2&
are different for material &V3&.

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?

Check the entries in the key fields of use data structure &V1& and
checkbox structure &V2& for material &V3&.
Perhaps a key field is blank, or the values in &V1& and
&V2& do not match.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.