How to configure bpm_delete_only job?

Hello,

I want the bpm_delete_only job to have all processes deleted that completed 30 days ago.

I configured the following parameters (according to the job log):

Resident Policy for object selection is  instanceIds = [] ,  timePeriod = 30 ,  inError = true ,  ProcessDefinitionID = null ,  completedProcesses = true ,  cancelledProcesses = true ,  completedFrom = null ,  completedTo = null

But the scheduled job does not find any processes for deletion.

When I provide exactly a process id only, the bpm_delete_only job manages to delete the process.

Is the parameter "Completion_Time_Period" specifying the time period in days as I assumed?

Thanks for any help

Peter Kain