Flex setFormatOfRange not working on actionscript-created TextAreas.

Question

I have the following code:

var vg:VGroup = new VGroup();
var summary:TextArea = new TextArea();
summary.text = "something"
var tlf:TextLayoutFormat = new TextLayoutFormat();
tlf.fontSize = 18;
tlf.fontWeight = "bold";
tlf.color = 0xFF0000;
summary.setFormatOfRange(tlf, 0, 2);
vg.addElement(summary);

(the TextArea is a spark.components.TextArea)

This doesn't work, no errors or anything - it just does nothing to the text. The text is there - but without any kind of formatting.

However, I see examples where this works on the internet - but always when the TextArea isn't created dynamically.

Is what I'm trying to do even possible with a TextArea?