Using get_recent and others in a seperate plugin

Hello,

Trying to use SlimStat’s API in another plugin but I receive this when trying to display the info:

Fatal error: Call to a member function query() on a non-object in /wp-content/plugins/wp-slimstat/admin/view/wp-slimstat-db.php on line 19

The code I’m using is:

// Load WP SlimStat DB, the API library exposing all the reports
require_once(WP_PLUGIN_DIR.'/wp-slimstat/admin/view/wp-slimstat-db.php');

// Initialize the API. You can pass a filter in the options, i.e. show only hits by people who where using Firefox, any version
wp_slimstat_db::init('browser contains Firefox');

// Use the appropriate method to display your stats
echo wp_slimstat_db::count_records('1=1', '*', false);

Example as the example in http://wordpress.org/plugins/wp-slimstat/faq/ at the bottom.

Any ideas :)?