--- a/src/lte/helper/lte-helper.cc	Thu Oct 10 14:39:23 2013 +0200
+++ b/src/lte/helper/lte-helper.cc	Thu Oct 17 14:24:12 2013 +0200
@@ -661,7 +661,7 @@
 {
   NS_LOG_FUNCTION (this);
 
-  NS_ASSERT_MSG (m_epcHelper != 0, "dedicated EPS bearers cannot be set up when EPC is not used");
+  NS_ASSERT_MSG (m_epcHelper != 0, "dedicated EPS bearers cannot be set up when the EPC is not used");
   
   uint64_t imsi = ueDevice->GetObject<LteUeNetDevice> ()->GetImsi ();
   m_epcHelper->ActivateEpsBearer (ueDevice, imsi, tft, bearer);
@@ -725,7 +725,7 @@
 LteHelper::ActivateDataRadioBearer (Ptr<NetDevice> ueDevice, EpsBearer bearer)
 {
   NS_LOG_FUNCTION (this << ueDevice);
-  NS_ASSERT_MSG (m_epcHelper == 0, "this method must not be used when EPC is being used");  
+  NS_ASSERT_MSG (m_epcHelper == 0, "this method must not be used when the EPC is being used");  
   
   // Normally it is the EPC that takes care of activating DRBs
   // when the UE gets connected. When the EPC is not used, we achieve
@@ -748,6 +748,8 @@
 {
   NS_LOG_FUNCTION (this);
 
+  NS_ASSERT_MSG (m_epcHelper != 0, "X2 interfaces cannot be set up when the EPC is not used");
+
   for (NodeContainer::Iterator i = enbNodes.Begin (); i != enbNodes.End (); ++i)
     {
       for (NodeContainer::Iterator j = i + 1; j != enbNodes.End (); ++j)