Cannot upgrade quantities

[asappia]

Some customer told me (and I've verified) that when a customer place a product in the shopping cart, he/she cannot change quantities from the shopping cart page.

you may verify it at http://www.pastorinocasa.com/:
try adding a product, then go to the shopping cart
try change the quantity for that product.

I've tried to solve this issue, but I was unable to do it..
anyone may help ?

Thanks

[Ajeh]

It appears to be working fine ...

Were you able to fix this? If so, what was the solution?