diff --git a/public/js/wn/ui/tree.js b/public/js/wn/ui/tree.js
index 81c4295c71..2a36546c9e 100644
--- a/public/js/wn/ui/tree.js
+++ b/public/js/wn/ui/tree.js
@@ -113,10 +113,12 @@ wn.ui.TreeNode = Class.extend({
 			callback: function(r) {
 				$(me.$a).done_working();
 
-				$.each(r.message, function(i, v) {
-					node = me.addnode(v);
-					node.$a.data('node-data', v);
-				});
+				if (r.message) {
+					$.each(r.message, function(i, v) {
+						node = me.addnode(v);
+						node.$a.data('node-data', v);
+					});
+				}
 				
 				me.loaded = true;