[Flash8] duplicateMovieClip not working inside a function

Hi.

I have duplicateMovieClip action inside a fuction and it doesnt work, however it works when placed outside of this function, right where the function is defined, 1st frame.

// WORKS WHEN PLACED HERE image_mc.duplicateMovieClip(“newname”, this.getNextHighestDepth());

function fadeimage() {
var a:Number = 10;
var l:Number = 0;
var o:Number = 100;
var t:Number = 0;
image_mc.duplicateMovieClip(“newname”, this.getNextHighestDepth()); // DOESNT WORK HERE
this.onEnterFrame = function() {
if (t == a) {
delete this.onEnterFrame;
setscroll();
} else {
image_mc._alpha = Quart.easeOut(t, l, o, a);
t++;
}
};
}

fadeimage function is triggered when image file has been loaded to image_mc.

what am I doing wrong? please help!