calling wp_logout() before get_header() doesn't logout before header processed

I am creating a custom logout page as part of my template, full code below. I anticipated that by calling wp_logout() before get_header() that when header.php is processed the user will be in a ‘logged out’ state and thus show the logged out elements, however this is not the case so obviously something else going on here?

Any ideas?

I need this mostly because i have a non-wordpress, .ASPX web page that will call my page http://www.mydomain.com/logout to logout when the user finishes their activity .

<?php
/**
 * Template Name: Custom Logout
 *
 * A custom page template with sidebar.
 *
 * The "Template Name:" bit above allows this to be selectable
 * from a dropdown menu on the edit page screen.
 *
 * @package WordPress
 * @subpackage Twenty_Ten
 * @since Twenty Ten 1.0
 */

?>
<?php wp_logout(); ?>

<?php get_header(); ?>

<div class="box-traing">

	<div class="box-traingb">

		<div class="box-traingcontent" style="padding-bottom: 10px;">
			<div id="left-tr" style="width: 925px">
			<h2 style="margin-bottom:10px;"><?php the_title(); ?></h2>
			<?php if(have_posts()) : while(have_posts()) : the_post(); ?>
			<?php the_content(); ?>
			<?php endwhile; endif; ?>
			</div>
		</div>
	</div>
</div>

<?php get_footer(); ?>