.as file to fade in images not working all the time

Hello all,
I have 10 images that are set to a loop. I wrote a .as file to control how the fade it. The first one works great, but after that the fades seem to get less and less till the last one seems to just pop up on stage. Any ideas as to why this could be happening?
Here is my code:

package
{
import flash.display.MovieClip;
import flash.events.Event;
import flash.display.Bitmap;

public class Fade_In_Out extends MovieClip
{
	public function Fade_In_Out()
	{
		this.alpha = 0;
		this.addEventListener(Event.ENTER_FRAME, fade);
	}
	
	public function fade(event:Event):void
	{
		this.alpha += .04;
	}
}

}

Thanks so much in advance!