theme have a custom search form > can see in the demo but not in my site

Hi!

I've installed the relax theme: http://www.dpol.ru/ and as you can see in the demo it has a custom search box in the header on the right of primary links, but I can't see it in my site after installation.

I checked the page.tpl.php & I see a code for the search form there:

<?php if (is_array($primary_links)) : ?>
		<div id="primaryMenu">
            <ul><?php foreach($primary_links AS $links){ echo '<li>'. l($links['title'], $links['href']). '</li>'; }; ?></ul>
			<?php print $search_box; ?>
		</div>
	<?php endif; ?>

I also read about template.php and search-block-form.tpl.php, I'm not sure they'd help in this case.

I tried also simple things like removing the search box I already had (from Administer > Site building > Blocks) thinking there might be a conflict between 2 search boxes, then tried to move my search box to the header ..

Note that I use Drupal 5.3 & have no PHP experience, please if the solution is PHP related give me an explanation for dummies :D

Thanks for your time!