Automate lightbox group rel [not plugin] w/ explode?

I’m having trouble automating the group rel for lightbox 2. I’ve searched the forums but it seems that all topics relate to the plugin, which I don’t wish to use. Here’s an idea I had, which didn’t pan out.

<div id="thumbslider">
<?php
$thumbslide = get_post_meta($post->ID, "thumbslide", false);
if ($thumbslide[0]=="") { ?>

<!-- If there are no custom fields, show nothing -->

<?php } else { ?>

<?php foreach($thumbslide as $thumbslide) {
$temp = explode("&", "$thumbslide");
$thumbsmall = $temp[0];
$thumbslidelarge = $temp[1];
$group = $temp[2];
echo '<a href="'.$thumbslidelarge.'" rel="lightbox['.$group.']"><img src="'.$thumbsmall.'" />
</a>';
} ?>

<?php } ?>
</div>

https://varriaga.com/portfolio/

I was trying to get the group from a custom field that I used to display the images and link them. Oddly enough, I don’t get an error message. the thumbs load just fine, but when clicked on, the image does not load.

I’d appreciate any help.

I’d like to add, if it’s possible, I would prefer to use the post title as the group rel as it would require less for me to do. I explored that option to the best of my ability, but I couldn’t figure it out.