Feature layer has to be dynamic?

[LeiZhou]

I need to use a method to show the feature layer when selecting it (see my codes).  My question is that: if the layer is dynamic then everything shows up; but if the layer is a tiled layer, it can not show up or only show a small part of the layer.  Why would this happen? Do I have to use dynamic layer as a feature layer? Thanks!

private function featureLayerShowHandler(event:FlexEvent):void
   {
    var newLayer:FeatureLayer = event.target as FeatureLayer;
    myMap.lods = newLayer.graphicProvider.lods;
   }