SAP Message AUR078 - You are not permitted to maintain key dates for simulation period &1

Diagnosis Simulation period &v1& uses asimulation type, for which theCheck Key Date indicator is not set. However, theKey Date of Mass Simulation is not initial. Procedure This situation can only arise if you use a different simulation typesubsequently in the simulation period, or if you change the simulationtype itself. We recommend that you do not make such changes. Delete the simulation period and create it again from new.