Javascript problem with quantity input (+ and -)

Hi,
I'm developing a new site with Hikashop Business but both in product's page and in category view, clicking on quantity increment/decrement buttons (+ and -), quantity is not updated and an error is logged in the developer's console: "ReferenceError: hikashopQuantityChange is not defined"

I've tried to activate "Use AJAX when possible for add to cart buttons" but nothing changes.
Tried also to change template and to re-install Hikashop, without results.

Any ideas?
Thank you very much
Kind regards

It was due a conflict with ReReplacer plugin.
SOLVED