283,285c564,573
<     $node->og_groups = array_diff($node->og_groups, $form_values['remove_from']);
<     foreach ($remove_from as $gid) {
<       drupal_set_message(t('The %type has been removed from %group.', array('%type' => $type, '%group' => $user->og_groups[$gid]['title'])));
---
>     $newnodes = array_diff($node->og_groups, $form_values['remove_from']);
>     if (!$newnodes && variable_get('og_audience_required', FALSE)) {
>       drupal_set_message('You can not remove all audience groups. At least one group must remain.');
>       $changed = FALSE;
>     } else {
>        $node->og_groups = $newnodes;
>       foreach ($remove_from as $gid) {
>         drupal_set_message(t('The %type has been removed from %group.', array('%type' => $type, '%group' => $user->og_groups[$gid]['title'])));
>       }
>       $changed = TRUE;
287d574
<     $changed = TRUE;