Index: lams_central/web/includes/javascript/groupDisplay.js
===================================================================
diff -u -r94d0394d34137a78c2f75a8cf090245f2598969e -r0b3e2d202a59e6a760a54abdeca1b33f0f5986c7
--- lams_central/web/includes/javascript/groupDisplay.js	(.../groupDisplay.js)	(revision 94d0394d34137a78c2f75a8cf090245f2598969e)
+++ lams_central/web/includes/javascript/groupDisplay.js	(.../groupDisplay.js)	(revision 0b3e2d202a59e6a760a54abdeca1b33f0f5986c7)
@@ -531,7 +531,7 @@
 				data : "method=removeLesson&lessonID=" + lessonID,
 				type : "post",
 				success : function(json) {
-					if (json.removeLesson == "true") {
+					if (json.removeLesson == true) {
 						loadOrgTab(null, true);
 					} else {
 						alert(json.removeLesson);
Index: lams_monitoring/src/java/org/lamsfoundation/lams/monitoring/web/MonitoringAction.java
===================================================================
diff -u -r7911b538e3fd0e8ae2bb56acac7eed836d4b2320 -r0b3e2d202a59e6a760a54abdeca1b33f0f5986c7
--- lams_monitoring/src/java/org/lamsfoundation/lams/monitoring/web/MonitoringAction.java	(.../MonitoringAction.java)	(revision 7911b538e3fd0e8ae2bb56acac7eed836d4b2320)
+++ lams_monitoring/src/java/org/lamsfoundation/lams/monitoring/web/MonitoringAction.java	(.../MonitoringAction.java)	(revision 0b3e2d202a59e6a760a54abdeca1b33f0f5986c7)
@@ -574,18 +574,27 @@
     public ActionForward removeLesson(ActionMapping mapping, ActionForm form, HttpServletRequest request,
 	    HttpServletResponse response) throws IOException, JSONException, ServletException {
 	IMonitoringService monitoringService = MonitoringServiceProxy.getMonitoringService(getServlet()
-		.getServletContext());
-	long lessonId = WebUtil.readLongParam(request, AttributeNames.PARAM_LESSON_ID);
-	// if this method throws an Exception, there will be no removeLesson=true in the JSON reply
-	monitoringService.removeLesson(lessonId, getUserId());
+	.getServletContext());
 
+	long lessonId = WebUtil.readLongParam(request, AttributeNames.PARAM_LESSON_ID);
 	JSONObject jsonObject = new JSONObject();
-	jsonObject.put("removeLesson", true);
+
+	try {
+	        // if this method throws an Exception, there will be no removeLesson=true in the JSON reply
+	        monitoringService.removeLesson(lessonId, getUserId());
+	        jsonObject.put("removeLesson", true);
+
+	} catch (Exception e) {
+	    String[] msg = new String[1];
+	    msg[0] = e.getMessage();
+	 	 jsonObject.put("removeLesson", monitoringService.getMessageService().getMessage("error.system.error",msg));
+	}
+
 	response.setContentType("application/json;charset=utf-8");
 	response.getWriter().print(jsonObject);
 	return null;
     }
-
+	 	
     /**
      * <P>
      * This action need a lession ID, Learner ID and Activity ID as input. Activity ID is optional, if it is null, all