If qty its more than 1, the cart its always 1

Hi, I ve this plugin on many of my websites. The last update broke this plugin. When the Qty Field its more than 1 and you press the “add to cart” button, you will always add no more than one item to the cart.

For example:
If the number 2 appears in the quantity field and I press “Add to cart”, the cart will add only 1 item. So, for example, if i want to buy two apples, i will need to press two times the button “add to cart” cause the qty field doesn’t respect the number that figure there.

Please we need a solution cause its very important for our web sites.`

The page I need help with: [log in to see the link]