Problem Using add_post_meta()

I’m trying to add post metadata on a Custom Post Type, but didn’t display on the Control Panel of my Custom Post Type. I’m using this frontend code with html form.

$title = $_POST['titulo'];
$content = $_POST['contenido'];
$post_type = 'sgpa_proyecto';
$curso = $_POST['proyecto_curso'];

$new_post = array(
'post_title' => $title,
'post_content' => $content,
'post_status'   => 'publish',
'post_type'     => $post_type
);

$post_id = wp_insert_post($new_post);							add_post_meta($post_id, 'proy-curso', 'ELO-230',true);

Please Help!

https://wordpress.org/plugins/types/