Diagnosis
You want to assign one or more objects to a document. However, at leastone object does not have a master record in the SAP System.
Via settings in Customizing (Document management), you define for eachspecific status of each document type whether the system checks thatobjects to be assigned exist.

System Response
For this document with its current status, the system carries out anobject check.

Procedure
You can only assign objects that have master records in the SAP Systemto this document.