--- basic-energy-source-helper.cc	2014-02-11 09:49:35.719621000 +0100
+++ basic-energy-source-helper.cc	2014-03-06 21:07:59.996820000 +0100
@@ -43,12 +43,12 @@ 
 {
   NS_ASSERT (node != NULL);
   // check if energy source already exists
-  Ptr<EnergySource> source = node->GetObject<EnergySource> ();
-  if (source != NULL)
+  Ptr<EnergySourceContainer> sourceContainer = node->GetObject<EnergySourceContainer> ();
+  if (sourceContainer != NULL)
     {
       NS_FATAL_ERROR ("Energy source already installed!");
     }
-  source = m_basicEnergySource.Create<EnergySource> ();
+  Ptr<EnergySource> source = m_basicEnergySource.Create<EnergySource> ();
   NS_ASSERT (source != NULL);
   source->SetNode (node);
   return source;