[FMX]swapDepths inside function

I have a function to fade in and out four movie clips. This is the code:

function fadeSub(l) {
 for (k=0; k<but.length; k++) {
  if (k != l) {
   this["sub_"+but[k]].onEnterFrame = function() {
	this._alpha += (0-this._alpha)/3;
	if (this._alpha < 5 ) {
	 this._alpha = 0;
	 delete this.onEnterFrame;
	}
   };
  } else {
   this["sub_"+but[k]].onEnterFrame = function() {
	this._alpha += (99-this._alpha)/12;
	if (this._alpha > 98) {
	 this._alpha = 99;
	 delete this.onEnterFrame;
	}
   };
  }
 }
}

I call the function with:

 clip.onRelease = function() {
  fadeSub(this.i);
 };

I have buttons inside the sub_mc’s that aren’t working because of the depths. How doI integrate a swapDepth in the fadeSub function?

Donald