Index: moodle/mod/lamslesson/callback.php
===================================================================
diff -u -r458edcd7121d8676f627e7f74a06952a54423bf6 -r63b37a77d3846f31e26052249099a01d2be7821f
--- moodle/mod/lamslesson/callback.php	(.../callback.php)	(revision 458edcd7121d8676f627e7f74a06952a54423bf6)
+++ moodle/mod/lamslesson/callback.php	(.../callback.php)	(revision 63b37a77d3846f31e26052249099a01d2be7821f)
@@ -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';
+
 ?>