Button click not regognized

Question

I'll try and be brief concerning this puzzling dilemma.
I have a movie clip on stage; instance name: "slide_mc"
on the enterFrame of slide_mc, I fill slide_mc by using: this.attachMovie (_global.myNewCip,"newMC",1);  // _global.myNewCip holds the linkage identifier
Throughout my swf, I use attachMovie to swap out new movie clips in slide_mc like this:
this.slide_mc.unloadMovie ();  //clear contents of slide_mc
slide_mc.attachMovie  (_global.myNewCip,"newMC",1);
There is a button on the movie clip I just attached to slide_mc. Its instance name is: "pause_btn"
From the main timeline I try to detect a mouse click by using this code:
this.slide_mc.newMC.pause_btn.onRelease = function () {
    trace ("clicked pause");
The click is detected only for the first time I use attachMovie. After that, I get nothing. I thought it was because I was using "unloadMovie" but I've tested for that and that's not it.
In my brevity, if my problem is unclear, let me know and I'll supply more info
All code is in frame 1
Thanks for any help!
David

Answer 1

A quick follow up. I now realize I have the same issue with a listener not being able to detect the end of an FLV. I tried the same fix but it doesn't seem to work.
After the attachMovie code, I am now calling a function I created called updateListener. It looks like this:
var listener:Object = new Object ();
listener.complete = function (eventObject:Object):Void  {
     trace ("end of flv");
this.slide_mc.newMC.clip1_FLVPlybk.addEventListener ("complete",listener);
The trace is not working.
Using this same technique (assigning a function after every time I used attachMovie) worked fine for recognizing the buttons, and I figured it would work for detecting these other issues. Maybe I'm doing something wrong (obviously!)
Thanks for any light you might shed on the subject.
David