diff --git a/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java b/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java
index 0247544..6fc6d62 100644
--- a/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java
+++ b/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java
@@ -1859,7 +1859,8 @@
         this.switchLinks = new HashMap<Long, Set<Link>>();
         this.quarantineQueue = new LinkedBlockingQueue<NodePortTuple>();
         this.maintenanceQueue = new LinkedBlockingQueue<NodePortTuple>();
-
+        this.remoteSwitches = new HashMap<Long, IOFSwitch>();
+        
         this.evHistTopologySwitch =
                 new EventHistory<EventHistoryTopologySwitch>("Topology: Switch");
         this.evHistTopologyLink =
diff --git a/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImpl.java b/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImpl.java
index 98605b2..249d626 100644
--- a/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImpl.java
+++ b/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImpl.java
@@ -106,7 +106,8 @@
             /*
              * retry till we succeed?
              */
-        	log.error("addOrUpdateLink(): titan exception {} {}", new Object[]{op, lt});
+        	log.error("addOrUpdateLink(): titan exception {} {} {}", new Object[]{op, lt, e.toString()});
+        	e.printStackTrace();
         }
 	}
 	
@@ -159,7 +160,8 @@
             /*
              * retry till we succeed?
              */
-        	log.error("deleteLink(): titan exception {}", lt);
+        	log.error("deleteLink(): titan exception {} {}", new Object[]{lt, e.toString()});
+        	e.printStackTrace();
         }
 	}