Actionscript 2.0

Assets contained in a Movie clip linked to a class (a movie clip subclass   ) are not automatically accessible and must be explicitly declared in the class. For a button named 'myButton_mc' on scene, add in your class properties:

ACTIONSCRIPT 2.0, ADDING AN EVENT HANDLE
TO A BUTTON IN A MOVIE CLIP

 Code:

var myButton_mc:MovieClip //..or Button but personnally I no more use button);

you can also declare a reference in one of the method 

that is fired at class instanciation;

Code:

var myButton=this.myButton_mc; //could be a long path here

then use your event handler as usual;

Code:

myButton.onRelease=function(){

   trace("myButton has been clicked")

}