Link to Post Parent from Attachment Page

I am trying to use the Gallery Shortcode to display all thumbnails underneath the large preview of an image on the attachment page.

Problem is I am having is I can’t seem to figure out how to get it to echo the post parent ID.

Here is the shortcode I am using, it only echos images that are in the main library of the Media section that are not attached to a post.

<?php echo do_shortcode(‘[gallery columns="7" id="<?php get_ID($post->post_parent); ?>"]‘); ?>

For example, I am trying to get the gallery of this post : http://www.sunboil.com/2008/12/20/retribution-gospel-choir-bottom-of-the-hill-20080708/

To be have displayed thumbnails underneath the large preview like here : http://www.sunboil.com/2008/12/20/retribution-gospel-choir-bottom-of-the-hill-20080708/retribution_gospel_choir_20080708_4/

You can see where the wrong images are being displayed.