That's too bad. I did test now on a local demo and it does work. Did you replace the entire
Code:
<div id="header-icons"><?php echo PAYMENT_ICON; ?></div>
by
PHP Code:
<div id="header-icons">
<img src="<?php  echo $template->get_template_dir('',DIR_WS_TEMPLATE, $current_page_base,'images').'/'.'payments.png' ?>"   class="imgshadow_light" alt="payments"  /></div>
BTW: your live site has not been changed. Is your test site on line?

jpd