List sortItemsBy error

1

keep getting this error when I try to sort a listbox:

ReferenceError: Error #1069: Property sortItemsBy not found on fl.controls.List and there is no default value.
at map_bugfixes_fla::mc_maps_1/map_bugfixes_fla::frame1()

Here’s my code to populate the listbox with xml data and then to sort it alphabetically:

function airlines_onLoaded_terminalb(e:Event):void
{
   xml = new XML(e.target.data);
   var il_airlines:XMLList = xml.airlines.terminalb.overview_yes.item;
   for(var i:uint=0; i<il_airlines.length(); i++)
   {
      mc_overview_airlines_list.lb_airlines.addItem({
         data:il_airlines.description.text()*,
         positionxdata:il_airlines.positionx.text()*,
         positionydata:il_airlines.positiony.text()*,
         varnamedata:il_airlines.varname.text()*,
         label:il_airlines.title.text()*});
   }
}
mc_overview_airlines_list.lb_airlines.sortItemsBy("label", "ASC");

Any help would by greatly appreciated.