Custome Metabox Issue

I’m trying to modify a ThemeTrust theme, and I understand that this snippet utilizes a metabox framework of some sort, but for anyone who actually understands php I was wondering if there and obvious reason why my Project Header Image isn’t rendering on the front end?

functions.php

$config = array(
    'id' => 'project_options',
    'title' => 'Project Options',
    'prefix' => $prefix."project_",
    'postType' => array('project'),
    'context' => 'side',
    'priority' => 'default',
    'usage' => 'theme',
    'showInColumns' => false
);

$project_header_meta_box = new mrMetaBox($config);

$project_header_meta_box->addField(array(
	'type' => 'Image',
	'id' => '_header',
	'label' => __('Project Header: ','themetrust'),
	'attachToPost' => true 

));

Project-single.php

<?php  $project_header = wp_get_attachment_image_src(get_post_meta($post->ID, "_ttrust_project_header", true), 'full'); ?>

        <img align="center" src="<?php  $project_header ?>" height="auto"  alt=""/>

Thanks for your time.