setNewTextFormat() - how?

programming flash
1

I would like to apply the text format style for this text field also:
But this code no works for those textfields.

email_txt.text = "@";
email_txt.setNewTextFormat(myTextFormat)
subject_txt.text = "Subject text";
subject_txt.setNewTextFormat(myTextFormat)
body_txt.text = "";
body_txt.setNewTextFormat(myTextFormat)

I have this style defined:

//START style format
myTextFormat = new TextFormat ();
myTextFormat.size = 10;
myTextFormat.bold = false;
myTextFormat.font = "Courier"
myTextFormat.color = "0x000000";
//END style format

Please look the attached file.