Index: /trunk/autoquest-core-tasktrees/src/main/java/de/ugoe/cs/autoquest/tasktrees/treeimpl/SequenceInstance.java
===================================================================
--- /trunk/autoquest-core-tasktrees/src/main/java/de/ugoe/cs/autoquest/tasktrees/treeimpl/SequenceInstance.java	(revision 2240)
+++ /trunk/autoquest-core-tasktrees/src/main/java/de/ugoe/cs/autoquest/tasktrees/treeimpl/SequenceInstance.java	(revision 2241)
@@ -74,5 +74,5 @@
      */
     @Override
-    public ITaskInstance get(int index) {
+    public synchronized ITaskInstance get(int index) {
         if (children == null) {
             throw new IndexOutOfBoundsException(Integer.toString(index));
@@ -87,5 +87,5 @@
      */
     @Override
-    public int size() {
+    public synchronized int size() {
         if (children == null) {
             return 0;