Hi Muhammad ,Abraham here.
Iv used the DSM Editor significantly,iv experienced such a thing as well.
The first thing I did is verify that the Regex captures the specific event on the DSM editor(The event is highlighted)
If this is so verify that the event ID U used during the mapping is a valid event ID and event category otherwise it won't parse it.
If the event ID and category is valid delete the mapping and create a new one on the DSM editor.
If this doesnt work open a case with IBM, hope this helps
#QRadar#Support#SupportMigration