what you are trying to do is difficult.

when you set src="images/buttonPressed.gif", you are telling the browser to
download a new image are change the display of the object. when the object
is a imagebutton, the onclick is firing a postback, which is also a download
request. becuase the main page is being replaced, the gif download is
canceled.

to do what you want if you really want to:

1) precache the "button pressed image"

<script>
   var imgButtonPressed = new Image ();
   imgButtonPressed.src = "images/buttonPressed.gif";
</script>

2) on the image buttons click cancel the postback, change the image and
queue up a new submit.

<script>
   function onClick(e)
   {
        if (e.src != img.src) {
                e.src = img.src;   // use cached image
                var s = "document.getElementById('" + e.id + "').click()";
                window.setTimeout(s,10); // give enough time to display
image before real postback
                return false;
       }
        return true;
    }
</script>

3) in the code behind, add the onclick handler

button.Attributes.Add("onclick","return onClick(this);")

-- bruce (sqlwork.com)