Order Out of Stock not working

Hi, I have a shop on OC 2.1.0.1 here : http://www.vente-pieces-agricoles.com.
Checkout out of stock is set to yes in settings, but when I want to add a product that is out of stock I have the alert message "Error! Only 0 items available!" and product is not add to cart.
You can try with this product that is out of stock : http://www.vente-pieces-agricoles.com/i ... t_id=32154
Any idea ?
thank you for your help

Yeah, I don't know if this has been addressed, but check this out:

http://stackoverflow.com/questions/1140 ... n-opencart