Professional :: FontDescription Could Not Be Found?

I wanted to load an external swf file in to a FLA file i used the code
 
var my_Loader:Loader = new Loader();
addChild(my_Loader);
var my_url:URLRequest=new URLRequest("external.swf");

[Code].... 
 
but when it loads I get the error
  
flash Error #1014: Class flash.text.engine::FontDescription could not be found.
 
I googled but the only thing I found was to place
 
var font:FontDescription = new FontDescription();
font.fontName = "Arial";
 
in the actions (Yes Arial is the font I am using)
 
The external loads fine and runs with out any errors alone.