--- privatemsg.module	2008-03-20 12:40:34.000000000 +0800
+++ privatemsg.module	2008-03-20 13:17:28.000000000 +0800
@@ -894,7 +894,7 @@ function privatemsg_list_form($messages,
       '#type' => 'checkbox',
     );
     $form['messages'][$message->id]['type'] = array(
-      '#value' => check_plain($message->type),
+      '#value' => (check_plain($message->type) != '' ? t(check_plain($message->type)) : ''),
     );
     $form['messages'][$message->id]['user'] = array(
       '#type' => 'value',