--- a/samples/main-ns2-mob.cc	Thu Jun 25 09:07:31 2009 +0200
+++ b/samples/main-ns2-mob.cc	Thu Jun 25 09:07:44 2009 +0200
@@ -34,5 +34,7 @@
   Simulator::Stop (Seconds (10.0));
   Simulator::Run ();
   Simulator::Destroy ();
+
+  os.close ();
   return 0;
 }