diff --git a/cs656/lab4/PresenceServiceImpl.java b/cs656/lab4/PresenceServiceImpl.java
index dad2b13..aeb761e 100644
--- a/cs656/lab4/PresenceServiceImpl.java
+++ b/cs656/lab4/PresenceServiceImpl.java
@@ -145,7 +145,11 @@ public class PresenceServiceImpl implements PresenceService
             System.out.println("DEBUG: DOM received:\n" + dom.getText());
             Document d = dom.getDocument();
             Node root = d.getFirstChild();
+            if (root == null)
+                System.err.println("listRegisteredUsers(): Error: root node not found");
             NodeList nl = root.getChildNodes();
+            if (nl == null)
+                System.err.println("listRegisteredUsers(): Error: nl is null");
             for (int i = 0; i < nl.getLength(); i++)
             {
                 Node n = nl.item(i);
@@ -161,7 +165,7 @@ public class PresenceServiceImpl implements PresenceService
             ioex.printStackTrace();
         }
 
-        RegistrationInfo[] dum = null;
+        RegistrationInfo[] dum = new RegistrationInfo[1];
         return users.toArray(dum);
     }