Subcategory thumbnails within parent category

Hey everyone.

I’m using the Categories Images plugin to try and show a thumbnail and a link to subcategories within any parent category page.

I have created a child theme and am editing in the archive.php file within the child theme and I have this but it doesn’t produce any results (the image part).

This is my code so far:

	
		<?php
			$cat = get_category( get_query_var( 'cat' ) );
			$cat_id = $cat->cat_ID;
			$child_categories=get_categories(
    			array( 'parent' => $cat_id )
			);
		?>
		
		<ul>

		<?php
		foreach ( $child_categories as $child ) {
    		// Here I'm showing as a list...
    		echo '<li>';
    		
    	?>
    	
    	<img src="<?php echo z_taxonomy_image_url($cat->term_id); ?>" />
    	
    	<?php
    	
    		echo '<a href="/'.$child ->slug.'">'.$child ->cat_name.'</a>';
    		echo '</li>';
		}
		?>
		
		</ul>

	</div>

And this is the documentation for the Categories Images plugin:

http://zahlan.net/blog/2012/06/categories-images/

I hope someone can show me the errors of my ways?

Thanks!

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