Data were imported from Fogbugz to JIRA via Fogbugz Importer (Import from database) - one of the option offered by JIRA. All looks good execpt that the actions were not imported to JIRA as shown below. Looks like the event description is missing, JIRA only import when there is comment added.
i.e.
Original in Fogbugz:
Opened by User B
Assigned to user A
Edited by user A
"Editing....."
in JIRA
Created by User B
Commented by user A
"Editing ......"
--> The actions of "Assign" and "Edit" were missing if no comment associated with that event