Adding FONT for a new TEXT LAYER :)

Hi guys,

I'm adding a text layer and i'm trying to change a FONT but it's doesnt work.

How can I make it works?

this is my code:

{

var proj=app.project.activeItem;

var myTextLayer=proj.layers.addText();

var textProp = myTextLayer.property("Source Text");

var textDocument = textProp.value;

textDocument.font = "Arial";

textDocument.text = "Hello world";

textProp.setValue(textDocument)

}