diff --git a/javascript/RelationComplexTableField.js b/javascript/RelationComplexTableField.js
index 2e98a29e5..1d490a678 100644
--- a/javascript/RelationComplexTableField.js
+++ b/javascript/RelationComplexTableField.js
@@ -4,7 +4,7 @@ var checkedListField = 'selected';
 var checkedArray = null;
 
 Event.observe( window, 'load', function() {
-	if($('sitetree')) {
+	if(typeof $('sitetree').observeMethod != 'undefined') {
 		$('sitetree').observeMethod( 'NodeClicked' , function() {
 			checkedListNameArray = null;
 			checkedArray = null;