textField inside button

[lobo]

I have created a button in library, and would like to addNewText in the first frame on the second layer of this button(here is the code which creates the button):
fl.getDocumentDOM().library.addNewItem("button", "Buttons/btn");

var closeBtn = fl.getDocumentDOM().library.findItemIndex("Buttons/btn");
var closeBtn_timeline = fl.getDocumentDOM().library.items[closeBtn].timeline;

closeBtn_timeline.addNewLayer("btn text","normal",false);

closeBtn_timeline.currentLayer = 0;
closeBtn_timeline.insertBlankKeyframe(3);

closeBtn_timeline.currentLayer = 1;
for (var i=1; i<4; i++){
closeBtn_timeline.insertBlankKeyframe(i);
}