Revisted underline text

Underlined Text On (rollOver)
Is there an action script to do on (rollover) underline text? It would be on a button that would also, on (release) gotoAndPlay a frame. I know you can have a movie with AS like this:

on (rollOver) {
myformat = new TextFormat();
myformat.color = 0xffffff;
myformat.underline = true;
textfeild.setTextFormat(myformat);
}
on (rollOut) {
myformat = new TextFormat();
myformat.color = 0xffffff;
myformat.underline = false;
textfeild.setTextFormat(myformat);
}

But when I add the on (release) to the movie it doesnt advance the timeline on (release). And when I change the file to a button instead of a movie clip it doesnt do the underline on (rollOver).
Does anyone have any easy advice?
Thanks