             
             if (targetNavigator is TabbedViewNavigator)
             {
-                targets.push(TabbedViewNavigator(targetNavigator).tabBar);
-                explicitIncludeInLayout = TabbedViewNavigator(targetNavigator).tabBar.includeInLayout; 
-                TabbedViewNavigator(targetNavigator).tabBar.includeInLayout = false;
+                var tabBar:ButtonBarBase = TabbedViewNavigator(targetNavigator).tabBar;
+                
+                if (tabBar)
+                {
+                    targets.push(tabBar);
+                    explicitIncludeInLayout = tabBar.includeInLayout; 
+                    tabBar.includeInLayout = false;
+                }
             }
             else if (targetNavigator is ViewNavigator)
             {
-                targets.push(ViewNavigator(targetNavigator).actionBar);
-                explicitIncludeInLayout = ViewNavigator(targetNavigator).actionBar.includeInLayout; 
-                ViewNavigator(targetNavigator).actionBar.includeInLayout = false;
+                if (actionBar)
+                {
+                    targets.push(actionBar);
+                    explicitIncludeInLayout = actionBar.includeInLayout; 
+                    actionBar.includeInLayout = false;
+                }
             }
             
             if (cachedNavigator)

            if (actionBar && actionBar.titleDisplay
                && (actionBar.titleDisplay is DisplayObject)
                && DisplayObject(actionBar.titleDisplay).visible)
                DisplayObject(actionBar.titleDisplay).cacheAsBitmap = false;
            
            if (cachedTitleGroup)
                removeComponentFromContainerSkin(cachedTitleGroup, actionBar.skin);

        if (targetNavigator == parentNavigator)
        {
            if (targetNavigator is TabbedViewNavigator)
            {
                var tabBar:ButtonBarBase = TabbedViewNavigator(targetNavigator).tabBar;
                
                if (tabBar)
                    tabBar.x = -slideDistance;
            }
        }
        else
        {
            if (targetNavigator is ViewNavigator && actionBar)
                actionBar.x = -slideDistance;
        }
        
        targetNavigator.contentGroup.x = -slideDistance;
