Why isn't the result of an OpenQuery refreshing?
The lastLogon attribute reflects the last interactive logon, not the last network-based logon

More info found here

This is some excellent information from this site


  Another twist: Active Directory does NOT replicate the LastLogon
  attribute across domain controllers. So in order to get an accurate
  value, you need to obtain the LastLogon value for the same user from
  all your domain controllers and accept the value that is highest.