Help!

Trying to do a simple thing, load a textfield into an empty movie clip

Here is the code

clip=createEmptyMovieClip(“clip1”,2);

//clip.createTextField(“my_txt”,1,300,20,60,60);
this.createTextField(“my_txt”,1,300,20,60,60);

my_txt.multiline = true;
my_txt.wordWrap = true;
var my_fmt:TextFormat = new TextFormat();
my_fmt.color = 0xFF0000;
my_fmt.underline = true;
my_txt.text = “Text.”;
my_txt.setTextFormat(my_fmt);

The problem is that
this.createTextField(“my_txt”,1,300,20,60,60); works

but what I want to do doesn’t work

clip.createTextField(“my_txt”,1,300,20,60,60);

Why???