***************
*** 84,89 ****
        $delta = $form_state['values']['delta'];
        $class = $form_state['values']['css_class'];
  
        db_query("DELETE FROM {block_class} WHERE module = '%s' AND delta = '%s'", $module, $delta);
  
        if (!empty($class)) {
--- 84,95 ----
        $delta = $form_state['values']['delta'];
        $class = $form_state['values']['css_class'];
  
+       //$delta is null if this is the add block form
+       if ($form_state['values']['form_id'] == 'block_add_block_form') {
+         $lastBlock = db_last_insert_id('blocks', 'bid');
+         $delta = db_result(db_query('SELECT delta FROM {blocks} WHERE bid = %d', array($lastBlock)));
+       }
+ 
        db_query("DELETE FROM {block_class} WHERE module = '%s' AND delta = '%s'", $module, $delta);
  
        if (!empty($class)) {