Update ecommerce-product-catalog.php

 Product catalog plugin is currently hard coding the plugins directory path.

Hard coding the plugins directory path only works for standard WP implementations. If wp-content is not in the same directory as the standard WP code then the plugin does not work anymore. 
WP codex (http://codex.wordpress.org/Function_Reference/wp_register_style) suggest "You should never hardcode URLs to local styles..."
Issue reference #1
The fix is using the plugins_url() function to get the correct directory name instead of /wp-content/plugins/.
Please update