entitykill objective issue

NullReferenceException: Object reference not set to an instance of an object
  at ObjectiveEntityKill.InternalToParametersDictionary (System.Collections.Generic.Dictionary`2[System.String,System.Object]& parameters) [0x00000] in <1a9a42033d954c90b0948926dec1ee9c>:0
  at BaseObjective.ToParametersDictionary () [0x00067] in <1a9a42033d954c90b0948926dec1ee9c>:0
  at Services.Analytics.Events.QuestProgressionEventData..ctor (BaseObjective objective) [0x0016d] in <1a9a42033d954c90b0948926dec1ee9c>:0
  at Quest.refreshQuestCompletion (...)
  at Quest.RefreshQuestCompletion (...)
  at ObjectiveEntityKill.Refresh ()
  at ObjectiveEntityKill.Current_EntityKill (EntityAlive, EntityAlive)
  at QuestEventManager.EntityKilled (EntityAlive killedBy, EntityAlive killedEntity)