case index number

How to prevent wrong case index number on new process ?


I'm actually with bonita 5.2.

I've actually a strange behavior on bonita about case index number.

My actual case index number for active workflow is : #28 and i need to purge every weeks the history.

But, i have some old wf, always open named, by example : WF_TEST_MYNEWPROCESS - #30.
I have to keep it because, it's not finished and still opened and needed to be complete by people.

When i try to start another workflow, the #29 is ok, but starting a second wf name #30 will be blocked and I see why.