WP E-commerce cart variations not validating

Hi,
I could have sworn this used to work on the WP E-commerce site Im working on, and the underlying store code has not changed since to my knowledge, but now it is not validating (anymore?).
For products with a variation, a customer can add the product to cart without selecting a variation first.
I need this to validate so it is not allowed to be added without first selecting a variation, ie size.

website: http://redcoral.com.au/products-page/

wp e-commerce version: Version 3.8.7.1 – WordPress version: 3.2.1
I tried reverting to twentyeleven theme, and the same problem occurred, so don’t believe it is a theme issue (nor any support thus far on the official WPEC forums).

Please have a look at the site, and code.
If you require more details let me know.

How can this be fixed?

Thanks