Diagnosis
You are trying to insert anassignment set. Thesettings for the assignment type of theworklist for object assignment only allowtime-dependent objectassignments. In this case no validity period has been specified.

System Response
The insertion of an assignment set without an effective validity periodis rejected.

Procedure
Enter data for the assignment set in the Effective from andEffective to fields on the tab page Attributes of AssignmentSet.