Javascript image swap - from flash

I have the following code in my html page:

<script>
<!-- Flash image swap code

if (document.images){

img1= new Image(468,288); 
img1.src="images/_placeholder.jpg";

img2= new Image(468,288); 
img2.src="images/_placeholder_2.jpg"; 

img3= new Image(468,288); 
img3.src="images/_placeholder_3.jpg";

img4= new Image(468,288); 
img4.src="images/_placeholder_4.jpg";

}

function change(changingImage, newImage){

changingImage.src = newImage.src;

}


//-->
</script>

The image thats already there has an id tag “img1” a name “img1”

Then in my flash movie I have:

btn_02.onRelease = function (){ 
          getURL("javascript:change(img1, img2)"); 
}

But nothing happens. Clearly ive assed up something somewhere. Any Ideas?

PS,
This is how the link should be in HTML:

<a href="#" onClick="change(img1, img2)">change to image 2</a>