[jQuery] I can't specify the photos width and height

Hi,
I have created a jCarousel photo gallery using drupal, it takes the
photos dynamically from drupal moduke, its work fine, but i can't
control the photos width and height, it takes it as it is stored in
drupal module.... what i should do.....
furthermore i specified it in my configuration, but it isn't
applied.... but the scroll property  is  applied right... why?!!!

    jQuery(document).ready(function() {
        jQuery('#mycarousel').jcarousel({
            scroll: 3,
            itemwidth : 100,
            itemheight : 80
        });
    });
Thanks for your support,