Status management: Please check status for reference object

What causes this issue?

You have attempted to enter maintenance processing data or maintenance
planning data or to assign the <DS:GLOS.reference_object>reference
object</> to a service contract.

System Response

The status of the <DS:GLOS.reference_object>reference object</> does
not allow maintenance processing data or maintenance planning data to
be entered or to assign this to a service contract.

How to fix this error?

Check the status of the reference object.

Error message extract from SAP system. Copyright SAP SE.