Array returns "undefined" in output?

On the timeline, I set up an array with ‘section’ names. When the mouse is clicked, a listener traces the section name to output.

 
var pageName:Array = new Array();
pageName [0] = "newsHolder";
pageName [1] = "aboutHolder";
pageName [2] = "reelHolder";
pageName [3] = "printHolder";
pageName [4] = "radioHolder";
pageName [5] = "miscHolder";
pageName [6] = "contactHolder";
 
(...)
 
trace ("New page selected "+pageName[selPageNum]);
trace ("Instance name is "+pageName[selPageNum]);
trace ("Current name is "+pageName[curPageNum]);

That works fine. But I also have a button on the stage:

 
on (release) {
trace ("testing "+pageName [0]);
}

But this returns “testing undefined”.

Where am I screwing up?