font embed dynamically problem

Hi I need to rotate dynamic text box, when it rotate then it's text goes unvisible, I need to embed font dynamically I tried this but it dosen't work.

function change_text(event:Event) {

    var tf:TextFormat = new TextFormat();

    tf.font = new String(font_list.selectedItem.data);

    displayer.embedFonts=true

    displayer.setTextFormat(tf);

    displayer.text = sampletext.text;

}