In contact us this is the wrapper:
'<div class="buttonRow forward"><?php echo zen_image_submit(BUTTON_IMAGE_SEND, BUTTON_SEND_ALT); ?></div>
<div class="buttonRow back"><?php echo zen_back_link() . zen_image_button(BUTTON_IMAGE_BACK, BUTTON_BACK_ALT) . '</a>'; ?></div>
<?php'

I tried putting this into submit block but still no luck