Index: /trunk/autoquest-core-tasktrees/src/main/java/de/ugoe/cs/autoquest/tasktrees/temporalrelation/utils/MostSimilarTaskDeterminer.java
===================================================================
--- /trunk/autoquest-core-tasktrees/src/main/java/de/ugoe/cs/autoquest/tasktrees/temporalrelation/utils/MostSimilarTaskDeterminer.java	(revision 1965)
+++ /trunk/autoquest-core-tasktrees/src/main/java/de/ugoe/cs/autoquest/tasktrees/temporalrelation/utils/MostSimilarTaskDeterminer.java	(revision 1966)
@@ -27,4 +27,5 @@
 import de.ugoe.cs.autoquest.tasktrees.treeifc.DefaultTaskTraversingVisitor;
 import de.ugoe.cs.autoquest.tasktrees.treeifc.IEventTaskInstance;
+import de.ugoe.cs.autoquest.tasktrees.treeifc.IOptionalInstance;
 import de.ugoe.cs.autoquest.tasktrees.treeifc.ISelectionInstance;
 import de.ugoe.cs.autoquest.tasktrees.treeifc.IStructuringTemporalRelationship;
@@ -827,4 +828,7 @@
                         eventTaskInstance = ((ISelectionInstance) eventTaskInstance).getChild();
                     }
+                    else if (eventTaskInstance instanceof IOptionalInstance) {
+                        eventTaskInstance = ((IOptionalInstance) eventTaskInstance).getChild();
+                    }
                 }
                 while (!(eventTaskInstance instanceof IEventTaskInstance));