Error when Activated

Hi,

Trying out this plugin but I got this error as soon as I activated it.

Notice: wp_register_style was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.0.) in xxx/wp-includes/functions.php on line 4138