Only calling 5 gallery images from page?

Hi,
I am working on a wordpress site (v2.9.2) and have a gallery for each pf a specific page type. However the array populating the gallery (code from the page is below) is only returning 4 values maximum.

Here is a sample page where you can see what I am discussing:
https://111.223.226.6/~blomwark/projects/heritage

For example, the page linked above should have 9 images.

If I use the array to return text I can see it is displaying 4 values, so I can rule out a problem with the Lightbox etc.

Any help would be extremely apprecited.

Many thanks

<?php
	$args = array(
	  'post_type' => 'attachment',
	  'post_mime_type' => 'image/jpeg',
	  'post_status' => null,
	  'post_parent' => $page->ID,
	  'orderby' => 'menu_order',
	  'order' => 'asc'
	  );
	$attachments = get_posts($args);
	if ($attachments):
		$gallery = array();
		foreach ($attachments as $attachment):
			if ($attachment->menu_order==0):
				$cover['title'] = $attachment->post_title;
				$cover['image'] = wp_get_attachment_url($attachment->ID);
			else:
				$gallery[$attachment->menu_order]['title'] = $attachment->post_title;
				$gallery[$attachment->menu_order]['image'] = wp_get_attachment_url($attachment->ID);
			endif;
		endforeach;

		sort($gallery);

		$gallery_image = '<img src="'.$cover[image].'" alt="'.$cover[title].'" />';

		if (count($gallery)>0):
		?>
		<a href="<?php echo $gallery[1]['image']; ?>" rel="lightbox[]"><?php echo $gallery_image; ?></a>
		<p><a href="<?php echo $gallery[1]['image']; ?>" rel="lightbox[]">Click here for more images</a></p>
		<?php foreach ($gallery as $item): ?>

			<a href="<?php echo $item['image']; ?>" class="hidden" rel="lightbox[]">&nbsp;</a>

		<?php
 		else:
			echo $gallery_image;
		endif;
	    endif; ?>