Missed DataChangeSubscriber init

src/main/java/fr/ill/ics/nscclient/sessionmanagement/ServerSessionManager.java

@@ -116,6 +116,7 @@ public class ServerSessionManager {
         }
         
         // initialise DataAccessor
+        DataChangeSubscriber.getInstance(serverId).init();
         DataAccessor.getInstance(serverId).init();
         ServantManagerAccessor.getInstance(serverId).init();