flash - autosize dynamic textbox issue

Hello,

I am loading some dynamic text into a flash textbox and am using autosize to change the height, but it doesn't seem to be working. I'm tracing the height and it doesn't seem to change when I modify the contents of test.txt. I think i'm missing something relatively simple. Any help is appreciated!

Here's the code:

loadText = new LoadVars();
      loadText.load("test.txt");
      loadText.onLoad = function(success) {
            if (success) {
                  homeBox.html = true;
                  homeBox.htmlText = this.copyTxt;
                  homeBox.autoSize = true;
                  }
      };      
                trace(homeBox._height);