--- loncom/interface/lonnavmaps.pm	2018/12/29 23:24:40	1.545
+++ loncom/interface/lonnavmaps.pm	2019/01/16 20:23:37	1.546
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Navigate Maps Handler
 #
-# $Id: lonnavmaps.pm,v 1.545 2018/12/29 23:24:40 raeburn Exp $
+# $Id: lonnavmaps.pm,v 1.546 2019/01/16 20:23:37 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -1490,10 +1490,13 @@ sub render {
         if ($args->{'iterator_map'}) {
             my $map = $args->{'iterator_map'};
             $map = $navmap->getResourceByUrl($map);
-            my $firstResource = $map->map_start();
-            my $finishResource = $map->map_finish();
-
-            $args->{'iterator'} = $it = $navmap->getIterator($firstResource, $finishResource, $filterHash, $condition);
+            if (ref($map)) {
+                my $firstResource = $map->map_start();
+                my $finishResource = $map->map_finish();
+                $args->{'iterator'} = $it = $navmap->getIterator($firstResource, $finishResource, $filterHash, $condition);
+            } else {
+                return;
+            }
         } else {
             $args->{'iterator'} = $it = $navmap->getIterator(undef, undef, $filterHash, $condition,undef,$args->{'include_top_level_map'});
         }