diff -Naur a/includes/node_admin.inc b/includes/node_admin.inc
--- a/includes/node_admin.inc	2009-01-14 19:11:21.000000000 +0100
+++ b/includes/node_admin.inc	2009-11-11 00:52:45.738708036 +0100
@@ -65,7 +65,7 @@
     array('data' => t('Attendance'), 'field' => 's.attended'),
   );
 
-  $sql = "SELECT u.uid, u.name, s.* FROM {signup_log} s INNER JOIN {users} u ON u.uid = s.uid WHERE s.nid = %d";
+  $sql = "SELECT u.uid, u.name, s.* FROM {signup_log} s LEFT OUTER JOIN {users} u ON u.uid = s.uid WHERE s.nid = %d";
   $sql .= tablesort_sql($header);
   $result = db_query($sql, $node->nid);
 
@@ -178,7 +178,7 @@
     '#tree' => TRUE,
   );
   $placeholders = db_placeholders($_SESSION['signup_cancel_multiple_users']);
-  $query = db_query("SELECT u.name, u.uid, s.* FROM {signup_log} s INNER JOIN {users} u ON s.uid = u.uid WHERE s.sid IN (". $placeholders .")", $_SESSION['signup_cancel_multiple_users']);
+  $query = db_query("SELECT u.name, u.uid, s.* FROM {signup_log} s LEFT OUTER JOIN {users} u ON s.uid = u.uid WHERE s.sid IN (". $placeholders .")", $_SESSION['signup_cancel_multiple_users']);
   while ($signup = db_fetch_object($query)) {
     $key = $signup->sid;
     if ($signup->uid) {