wm triggers and wm.server.dispatcher:deleteExpiredUUID error

We are using IS6.1 and wm trigger receiving documents from gxs exterprise. No broker used.
There are error log on server below:
wm.server.dispatcher:deleteExpiredUUID:com.wm.app.b2b.server.ServiceException: cann’t delete document from history (the meaning is just translated from Chinese )
the server log is :
deleting expired uuids exception: com.wm.app.b2b.server.indoubtresolver.exceptions.ConnectionException:cann’t get jdbc connection

the trigger properties:
Exactly once:
Detect duplicates:true
Use history: False
History time to live: 2 hours

The questions are:

  1. do i have to set use hostory properties to true since the detect duplicates is true?
  2. how to deal with the error log? We don’t use jdbc for the trigger and we don’t use broker neigher. So how come the error contains jdbc connection.
  3. It is said the wm.server.dispatcher:deleteExpiredUUID is system default scheduler. But we’ve got two envioment , one for developping , the another is producion env. I found out the the production env don’t have this service in scheduler. So how does IS know when do start this service in scheduler?

Best Regards!