The Activity Line Graph of the Expired Alarms View displays activity details during the time duration you specify.
Expand the Day drop-down list to select the date for which the time duration displays. Select the time duration (1 Hour, 2 Hours, 4 Hours, 8 Hours, 24 Hours) for which you want to display alarm activity.
Select the 
button and drag on the timeline to define a range of
time for which you want to display the alarm activity.