Order Pages

My Blog has the pages listed across the top. They are not in alphabetical order and I can’t figure out how to get them there. It looks like this in the code

<div id="topright">
<ul>
  <?php wp_list_pages('depth=1&title_li=0&sort_column=menu_order'); ?>
  <li><a href="#searchform">search</a></li>
</ul>
</div>

how can I get it to go in alphabetical order?