Fix E_NOTICE on announcements

main/admin/system_announcements.php

@@ -231,11 +231,15 @@ if ($action_todo) {
                 );
 
                 if ($announcement_id !== false) {
+                    if (isset($values['group'])) {
                         SystemAnnouncementManager::announcement_for_groups(
                             $announcement_id,
                             array($values['group'])
                         );
-                    Display :: display_confirmation_message(get_lang('AnnouncementAdded'));
+                        Display:: display_confirmation_message(
+                            get_lang('AnnouncementAdded')
+                        );
+                    }
                 } else {
                     $show_announcement_list = false;
                     $form->display();
@@ -258,11 +262,15 @@ if ($action_todo) {
                     $sendMailTest
                 )
                 ) {
+                    if (isset($values['group'])) {
                         SystemAnnouncementManager::announcement_for_groups(
                             $values['id'],
                             array($values['group'])
                         );
-                    Display :: display_confirmation_message(get_lang('AnnouncementUpdated'));
+                        Display:: display_confirmation_message(
+                            get_lang('AnnouncementUpdated')
+                        );
+                    }
                 } else {
                     $show_announcement_list = false;
                     $form->display();