Index: lams_monitoring/web/includes/javascript/monitorLesson.js
===================================================================
diff -u -r0a6d83eb3e59f21ccfb53b0593c8d39da29be66e -re7b08ccbe2acd7966b75acbb62e95bfdda2e3bbd
--- lams_monitoring/web/includes/javascript/monitorLesson.js	(.../monitorLesson.js)	(revision 0a6d83eb3e59f21ccfb53b0593c8d39da29be66e)
+++ lams_monitoring/web/includes/javascript/monitorLesson.js	(.../monitorLesson.js)	(revision e7b08ccbe2acd7966b75acbb62e95bfdda2e3bbd)
@@ -1235,7 +1235,7 @@
 				if (isGate) {
 					var gateClosedIcon = activityGroup.find('.gateClosed');
 					
-					if (activity.gateOpen) {
+					if (activity.gateOpen && gateClosedIcon.length > 0) {
 						if (!gateOpenIconData) {
 							// if SVG is not cached, get it synchronously
 							$.ajax({