Wp-ecommerce Product Rating errors

I’m using wp-ecommerce and have a custom template which includes a call to the wpsc_product_rater() function.

The rating system displays fine, but when I make a rating the page reloads with the following errors:

Notice: Undefined index: voting_cookie in /var/www/wp-content/plugins/wp-e-commerce/wpsc-includes/ajax.functions.php on line 330 Notice: Undefined variable: prodid in /var/www/wp-content/plugins/wp-e-commerce/wpsc-includes/ajax.functions.php on line 346 Notice: Undefined index: ajax in /var/www/wp-content/plugins/wp-e-commerce/wpsc-includes/ajax.functions.php on line 348

The new rating doesn’t appear until I refresh the page again. So it seems the ratings are being made but there’s a kink in the process.