Fatal error: Call to undefined function wpsc_cart_item_count()

— I’ve just done a fresh install of WordPress 3.4

— I’ve downloaded and uploaded this new free eCommerce wordpress theme suggested by smashing magazine.

{ http://www.smashingmagazine.com/2011/10/19/free-e-commerce-wordpress-theme-balita/ }

— And I get this giant error on the homepage:

Fatal error: Call to undefined function wpsc_cart_item_count() in /home/content/97/8209697/html/websitename/wp/wp-content/themes/balita/header.php on line 78

Line 78 reads:

<div class="totalItem totalitems"><?php printf( _n('%d item', '%d items', wpsc_cart_item_count(), 'tokokoo'), wpsc_cart_item_count() ); ?></div>

Live Site at (http://tinyurl.com/cdva5aw)

Any pointers?

If you followed the install instructions with that theme, one of the steps was to add the WP e-Commerce plugin and activate it. wpsc_cart_item_count is a function of that plugin, so it is likely not currently activated.