Add to cart button not showing on variables

Hi all

The add to cart button is not showing on my variable products. It worked perfectly until I played around with a couple of plugins. I deactivated all plugins I installed, but it still there is a problem. I don’t know if a plugin left some code that messed up the button.

Here is a URL to my page:
http://mynunu.co.za/product/stickaroo-counting-sheep/

Thanks!