I see posts go on Twitter but I still get these errors which are always visible in WordPress Admin and I would like to remove those:
There's been an error posting your Twitter status! Visit your WP to Twitter settings page to get more information and to clear this error message.
One or more of your last posts has failed to send it's status update to Twitter. Your Tweet has been saved in your post custom fields, and you can re-Tweet it at your leisure.
200 OK: Success!
Sorry! I couldn't get in touch with the Twitter servers to post your new blog post. Your tweet has been stored in a custom field attached to the post, so you can Tweet it manually if you wish!