Index: moodle/mod/lamslesson/callback.php
===================================================================
RCS file: /usr/local/cvsroot/moodle/mod/lamslesson/callback.php,v
diff -u -r1.2 -r1.3
--- moodle/mod/lamslesson/callback.php	6 Jan 2012 13:23:00 -0000	1.2
+++ moodle/mod/lamslesson/callback.php	11 Apr 2017 18:02:49 -0000	1.3
@@ -48,4 +48,7 @@
 
 $gradebookmark = lamslesson_get_lams_outputs($user->username,$lamslesson,$user->username);
 
+// let LAMS know that mark retrieval process has finished successfully
+echo 'OK';
+
 ?>