The reasons may be:
1. Device is so busy that it couldn't send RTM to UI
2. There are some exceptions in UI's Java console
3. Device doesn't hit any rules (If no data means no top-nevents)
Scenario 1 - the RTM shows no data while the time axis keepsgoing as time elapses: It may be because there is no networktraffic passing through the device or the device is too busy tosend the real-time data.
Scenario 2 - the time axis of the RTM does no go as timeelapses: The RTM crashes because some unexpected error hashappened. User may need to close the UI and re-login the systemagain.