Attaching MovieClip from Library (Please help)

Hello

I have created a textfield and then attached a movieclip as a background on top of which I wanna place the text field just like a button.

Here is the code

var txt:TextField = new TextField();

var bg:MovieClipClass = new MovieClipClass( );
bg.addChild( txt );

txt.text = “Hello World!!”;
addChild(bg);

The movieclip and text field are displayed on the stage but the text field is not on top of the background clip it is always away from the clip I have even tried

assigning the moviclip x and y coordinate to text field but does not work.

Any help will be well appreciated

Thank in advance