Index: wp-admin/js/custom-navigation-dynamic-functions.dev.js
===================================================================
--- wp-admin/js/custom-navigation-dynamic-functions.dev.js	(revision 13312)
+++ wp-admin/js/custom-navigation-dynamic-functions.dev.js	(working copy)
@@ -180,7 +180,7 @@
 		inputdescription = '';
 	}
 
-	var count=document.getElementById('custom-nav').getElementsByTagName('li').length;
+	var count=document.getElementById('custom-nav').getElementsByTagName('li').length + 1;
 
 	var randomnumber = count;