showPermissionDialog with ExternalInterface (facebook/ flash)

I trying to pomp showPermissionDialog for allow the user to post something in a friend Wall.

I have the flowing javascript code:

  <script type="text/javascript">
    function showStreamPermissions() {
    FB.Connect.showPermissionDialog("publ开发者_开发知识库ish_stream", doResult);    
     }
 </script>

On may as3 class file i have this code to call showStreamPermissions:

protected function showPermissionDialog(e:MouseEvent):void {

  ExternalInterface.call("showStreamPermissions");

  }

But when i click the button to show Premonition Dialog , nothing happens?

Does anyone know why ?

Thanks.

MB

I figure what was the problem. It´s necessary to allow script access

params.allowScriptAccess="always";