The location based notification is not work on iOS 8

I use iphone 6, when I try to create a location based notification on Reminders app, I swiched to 'when I leave...' or 'when I arrive', I realise that the function is not working and no notification is pushed to my phone when I even have left the location 1 mile away...

I ensure that I have switched on 'Location-based alerts' in privacy setting and also have switched on general background refresh, as well as 'while using' in privacy > location services . When I set the location based notification of the Reminder, a geofence icon is appearing on the top right corner right next to the battery icon, however, no location based notification is delivered...

yet I have also turned on the notification of Reminders!.

Is that a bug or there is something more I need to modify ? Please help...