wp_insert_post in current blog

Hi! I’ve just created an WPMS installation with two sub-sites. They both share the same theme, and in one page, the user should be able to insert a post into the current site.

I’m trying to use the function switch_to_blog() to switch to the current blog and then insert the post with wp_insert_post() and update_post_meta() but the posts are always inserted into the main site.

Anybody knows what am I doing wrong? Here’s the code:

$title = $_POST['title'];
$author_id = $_POST['author_id'];
$reference = $_POST['reference'];
$blog_id = $_POST['blog_id'];

$my_post = array(
 'post_title' => $title,
 'post_status' => 'pending',
 'post_author' => $author_id,
 'post_type' => 'order'
);

switch_to_blog($blog_id);
$new_id = wp_insert_post( $my_post );
update_post_meta($new_id, "reference", $reference);
restore_current_blog();

Thanks in advance!