Diagnosis
You have tried to start a live posting run and generate documents (liveor simulated). This is only allowed for real payroll results.

Procedure
If you want to simulate the payroll run, for example, for personnelcost planning, please only create simulation documents, not livedocuments.
If you do want to start a live run, please deselect the 'SimulatePayroll' parameter (after choosing 'Cost Planning').