I cannot include a file in my plugin settings page

Question

I'm trying to create a settings page. If I print things within index, I can see it. If I try to include it, I can't see anything, neither errors.

add_options_page('My Plugin', 'My Plugin', 'manage_options', 'my-plugin', array('MyPluginSettings', 'index'));

my settings:

class MyPluginSettings
{
    public function index()
    {
        /* I can echo or print here and it works fine ...
         * But i can't require a file here ... nothing happens
         */
        require('existing/path/to/a/file.php');
    }
}

?>

What's wrong? Thanks.

Answer 1

Most likely the file cannot be found, I'm assuming the file you're trying to include is located in your theme folder, in that case you should use:

require_once( TEMPLATEPATH . '/file.php');

TEMPLATEPATH will return something like this: /home/user/httdocs/wp-content/themes/twentyeleven.

Worst case scenario you'll find a Fatal Error, but that'll help to find the problem.