Display custom field outside the loop

Question

Inside of my WordPress theme directory I have a standalone PHP file called image, this currently looks like this....

<?php
  define('WP_USE_THEMES', false);
  require('/home/mysite/public_html/wp-blog-header.php');
?>

<?php
  global $post;
  $post_id = 288;
  $header_image = get_post_custom_values('caption', $post_id);
    echo get_post_meta($post_id, 'caption', true);
?>

When I visit this site I want it to return the custom field value for 'caption' but I am getting nothing. I realise this page is outside of the loop but I thought I have included the wp-blog-header.php that it needed. Can anyone help?

Answer 1

<?php
  define('WP_USE_THEMES', false);
  require('wp-blog-header.php');
?>

<?php
    $post_id = 288;
    echo get_post_meta($post_id, 'caption', true);
?>

That part is enough - are you sure that this is the name of your custom field and the path to wp-blog-header is resolved and valid?