Change AlarmEvent property dynamically

I am trying to change an alarmEvent property dynamically by using a script (the objective is to allow the operator to add a note on the alarm), I have tried to set the ‘Label’ property of an alarmEvent by using the alarmEvent.set(Label, val), the value changes momentarily in the AlarmSummary then it returns to the default value configured on the Alarm. Is there another way to add a note on an alarmEvent?
Thanks in advance.