diff --git a/web-app/js/datasetExplorer/ext-i2b2.js b/web-app/js/datasetExplorer/ext-i2b2.js
index 2c6076efb..7afd49e10 100644
--- a/web-app/js/datasetExplorer/ext-i2b2.js
+++ b/web-app/js/datasetExplorer/ext-i2b2.js
@@ -50,7 +50,10 @@ Ext.ux.OntologyTreeLoader = Ext.extend(Ext.tree.TreeLoader, {
         getChildConceptPatientCounts(node);
         node.endUpdate();
         if (typeof callback == "function") {
-            callback(this, node);
+            //To do not fail when search criteria has changed in between.
+            if (node.getOwnerTree()) {
+                callback(this, node);
+            }
         }
     },