secondary_links on front page?

<div id="menu">
	<?php if (isset($primary_links)) { ?><?php print theme_menu_links($primary_links); } ?>
</div> <!-- end menu -->

<div id="sub_menu">
	<?php if (isset($secondary_links)) { ?><?php print theme_menu_links($secondary_links); } ?>
</div> <!-- end sub_menu -->

I am using PHPTemplate, and that code above is how I output my primary and secondary links as unordered lists.

The secondary_links are displayed like expected on all other pages than the front page. Why are the secondary_links hidden on the front page? Is there a way to make them appear on the front page?

I have searched for days, without finding a solutioin. A little help would be much appreciated!