ActionScript 3.0 :: Scrolling Externally Loaded Dynamic Text

I have a dynamic text field within my site that I want to load in text from an external .txt file. I also want to add a scrollbar to this field so that you can have more text than can fit in the textbox at anyone time. I have found this AS3 code to load the external text (from my 'vacancies.txt' file) in to my text box (vacanciesbox_txt):

Code:
var my_req:URLRequest = new URLRequest("vacancies.txt");
var my_loader:URLLoader = new URLLoader();
my_loader.addEventListener(Event.COMPLETE, loadText);
my_loader.load(my_req);
function loadText(event:Event):void{
vacanciesbox_txt.text = my_loader.data;
}

This all works fine and the text is loaded in as I want - The problem I have is that when I add a UIscrollbar to the dynamic text field from the flash components, it doesn't display and/or work when published.