Index: webform_alt_ui.js
===================================================================
RCS file: /cvs/drupal/contributions/modules/webform_alt_ui/webform_alt_ui.js,v
retrieving revision 1.1
diff -u -p -r1.1 webform_alt_ui.js
--- webform_alt_ui.js	11 Jan 2011 17:19:44 -0000	1.1
+++ webform_alt_ui.js	22 Mar 2011 00:02:41 -0000
@@ -38,8 +38,10 @@ Drupal.behaviors.webformAltUI = {
     if (!Drupal.behaviors.webformAltUI.activeTab) {
       var tab = {};
       tab.fieldset = $('.horizontal-tabs-pane:visible');
-      Drupal.behaviors.webformAltUI.activeTab = tab;
-      Drupal.behaviors.webformAltUI.tabActivated({}, tab);
+      if (tab.fieldset.length) {
+        Drupal.behaviors.webformAltUI.activeTab = tab;
+        Drupal.behaviors.webformAltUI.tabActivated({}, tab);
+      }
     }
 
     // Bind event handlers to update the submit button text.