diff --git a/core/tickets/serializers.py b/core/tickets/serializers.py
index f954130..0dd797c 100644
--- a/core/tickets/serializers.py
+++ b/core/tickets/serializers.py
@@ -62,7 +62,12 @@ class IssueSerializer(serializers.ModelSerializer):
                 if self.state_changes.count() > 0 else None
             last_comment = self.comments.order_by('-timestamp').first().timestamp if self.comments.count() > 0 else None
             last_mail = self.emails.order_by('-timestamp').first().timestamp if self.emails.count() > 0 else None
-            args = [x for x in [last_state_change, last_comment, last_mail] if x is not None]
+            last_assignment = self.assignments.order_by('-timestamp').first().timestamp if \
+                self.assignments.count() > 0 else None
+            last_relation = self.item_relations.order_by('-timestamp').first().timestamp if \
+                self.item_relations.count() > 0 else None
+            args = [x for x in [last_state_change, last_comment, last_mail, last_assignment, last_relation] if
+                    x is not None]
             return max(args)
         except AttributeError:
             return None