fix compile errors
diff --git a/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java b/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java
index 4e19013..6f7c9b7 100644
--- a/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java
+++ b/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java
@@ -1868,6 +1868,7 @@
         }
 
         // Initialize the link storage connector to the network map
+        this.linkStore = new LinkStorageImplStubs();
         this.linkStore.init("");
         
         ScheduledExecutorService ses = threadPool.getScheduledExecutor();