ActionScript 3.0 :: Create A Custom Format For A TextField Text?

I've created a custom format for a TextField text as below:

Code:
var _format:TextFormat = new TextFormat();
var _font:Font = new VerdanaPlain();
_format.font = _font.fontName;
_format.size = 12;

and then I've applied it to a TextField like so:

Code:
var _text:TextField = new TextField();
_text.setTextFormat(_format);
_text.text = "Here is some text";

and for some strange reason, the format does not seem to have any effect on the text in the text field. It still shows using default settings. And yes I have exported the font for linkage.