Index: trunk/quest-core-tasktrees/src/main/java/de/ugoe/cs/quest/tasktrees/treeimpl/TaskTreeNodeImpl.java
===================================================================
--- trunk/quest-core-tasktrees/src/main/java/de/ugoe/cs/quest/tasktrees/treeimpl/TaskTreeNodeImpl.java	(revision 469)
+++ trunk/quest-core-tasktrees/src/main/java/de/ugoe/cs/quest/tasktrees/treeimpl/TaskTreeNodeImpl.java	(revision 470)
@@ -255,9 +255,12 @@
       clone = (TaskTreeNodeImpl) super.clone();
       
-      clone.mChildren = new ArrayList<TaskTreeNode>();
-      
-      for (TaskTreeNode child : mChildren)
-      {
-        clone.mChildren.add(child.clone());
+      if (mChildren != null)
+      {
+        clone.mChildren = new ArrayList<TaskTreeNode>();
+      
+        for (TaskTreeNode child : mChildren)
+        {
+          clone.mChildren.add(child.clone());
+        }
       }