问SecurityError:错误#2142:安全沙箱违规

EN

SecurityError: Error #2142: Security sandbox violation: local SWF files 
cannot use the LoaderContext.securityDomain property. 
app:/Main.swf was attempting to load app:/assets/stories/bear.swf.

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               xmlns:ns1="*"
               applicationDPI="240" creationComplete="initApp(event)">
    <fx:Script>
        <![CDATA[
            import mx.events.FlexEvent;
            import flash.system.SecurityDomain;
            import flash.system.ApplicationDomain;

            protected function initApp(event:FlexEvent):void
            {
                var context:LoaderContext = new LoaderContext();
                context.securityDomain = SecurityDomain.currentDomain;
                context.applicationDomain = new ApplicationDomain();

                Story.loaderContext = context;
                Story.source = "app:/assets/stories/Bear1.swf";
            }

        ]]>
    </fx:Script>
    <s:SWFLoader id="Story" left="0" right="0" top="0" bottom="0" 
                 trustContent="true"
                 scaleContent="true"/>
</s:Application>