<header>
    <?php
    $theme_header_style = theme_get_setting('header_style');//the value is 1
    $header_path = "header_tpl_".$theme_header_style.".php";
    include_once $header_path;//includes header_tpl_1.php
    ?>
    <h1><?php print $site_name; ?></h1><!--this works-->
</header>

<h1>this will show up</h1>
<h1><?php print $site_name; ?></h1><!--this will not work just an empty h1-->
<p>this will show up on page.tpl.php as well</p>