Index: lib/accesslib.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/accesslib.php,v
retrieving revision 1.510
diff -u -a -w -b -B -r1.510 accesslib.php
--- lib/accesslib.php	16 Aug 2008 12:16:05 -0000	1.510
+++ lib/accesslib.php	18 Aug 2008 04:25:30 -0000
@@ -2779,6 +2779,7 @@
 function role_unassign($roleid=0, $userid=0, $groupid=0, $contextid=0, $enrol=NULL) {
 
     global $USER, $CFG, $DB;
+    require_once($CFG->dirroot.'/group/lib.php');
 
     $success = true;