Custom Categories List

Hello,
Im try to use this code to do a List of categories, but i want to show only the thumbnail, but not work, can help?

<ul>
					<?php
					$args=array(
					'orderby' => 'name',
					'order' => 'ASC'
					);
					$categories=get_categories($args);
					foreach($categories as $category) {
					echo '<li><a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "Ver postagens em %s" ), $category->name ) . '" ' . '>';
					if(has_category_thumbnail($category->term_id)) {
						the_category_thumbnail($category->term_id)
					}
					echo '</a></li>';
					}
					?>
					</ul>

https://wordpress.org/plugins/category-thumbnails/