Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.484
diff -u -p -r1.484 form.inc
--- includes/form.inc 20 Aug 2010 01:08:18 -0000  1.484
+++ includes/form.inc 23 Aug 2010 22:12:07 -0000
@@ -2798,6 +2847,9 @@ function theme_tableselect($variables) {
       drupal_add_js('misc/tableselect.js');
       array_unshift($header, array('class' => array('select-all')));
     }
+    else {
+      array_unshift($header, '');
+    }
   }
   return theme('table', array('header' => $header, 'rows' => $rows, 'empty' => $element['#empty'], 'attributes' => $element['#attributes']));
 }