                     delta = Math.max(getElementBounds.top - scrollRect.top, -scrollRect.height);  
             }
             break;
-            case ScrollUnit.PAGE_DOWN:
+            case NavigationUnit.PAGE_DOWN:
             {
                 // Align the top edge of the element to the top edge of the scrollRect.
                 // The element is the the first non-fully visible element below the scrollRect.

    {
        if (_target == value)
            return;
        clearCachedVirtualLayoutState();
        _target = value;
    }
    

     *  @playerversion AIR 1.5
     *  @productversion Flex 4
     */  
     public function getNavigationDestinationIndex(currentIndex:int, navigationUnit:uint):int
     {
        if (!target || target.numElements < 1)
            return -1; 
