inclued header

Hi all i have installed WHMCS in the same directory as my wordpress and i am trying integrate them. I actually pulled this off before but i completely forget what i done. I found some old files and what i had done before to make this work was i put the following into the header.tpl file of whmcs.

{php}
// including a php script directly from the template.
include(‘header-1.php’);
{/php}

I then created the file named header-1.php which i added the header code of the wordpress theme into it, but i also added the following

<?php
require(‘wp-blog-header.php’);
?>

If i open the header-1.php file directly on my browser it works fine. but when I add it to the header.tpl file of the whmcs and open the page i get the following.

Error establishing a database connection.

I seemed to have relicated what i have done before but this time im getting database connection errors. Has anyone any idea what iv done wrong this time. Any help would be great.

Thanks
Aiden