Plugin not triggering ping or other plugins

Hello

I have had a plugin developed that imports posts from an XML file into wordpress. The import works fine, but the published posts are not triggering pings or other plugins that act on a pubish event (e.g. a twitter posting plugin such as tweetly).

It uses the wp api.. inserts the post initially as “draft” with a ping_status of “open” the following code:

$my_post = array();
$my_post[‘post_title’] = $Heading;
$my_post[‘post_name’] = $post_slug;
$my_post[‘post_content’] = $Content;
$my_post[‘post_status’] = ‘draft’;
$my_post[‘post_author’] = $AutorID;
$my_post[‘post_category’] = array($term_id);

$my_post[‘ping_status’] = ‘open’;
$my_post[‘to_ping’] = ”;
$my_post[‘pinged’] = ”;
$my_post[‘post_date’] = $post_date;
$my_post[‘post_date_gmt’] = $post_date;
$my_post[‘post_type’] = ‘post’;

$post_ID = wp_insert_post($my_post);

do_action(‘publish_post’, $post_ID);
wp_publish_post($post_ID);

The posts are posted (added) and are published – and so this code seems to be working.

But – the posts are never pinged.. and the twitter plugin (tweetly) doesn’t pick it up either. Both of these work when manually adding a post.

Any advice / guidance would be appreciated.

Thanks in advance