Coupon codes ignored (nothing happens)

-- HikaShop version -- : 2.3.3
-- Joomla version -- : 3.3.6
-- PHP version -- : 5.5.17
-- Browser(s) name and version -- : Chrome 37.0.2062.120
-- Error-message(debug-mod must be tuned on) -- : no error message shown

I have configured my checkout to show the "Add Coupon" field, and have configured a coupon code ("sound14") giving 20% off all products. The "Add Coupon" field shows up, but regardless of the coupon code entered the following happens when I click on "Add":

- The first click does nothing
- The second click proceeds to the next page
- The coupon is NEVER shown in the cart, and never applied.
- No error messages are displayed.

The only time when the coupon appears to work is if I have "Auto load in cart if possible" turned on; but that is not the final solution.

Great, upgrading FaLang solved the problem! (Never thought that this would be the problem -too far away)
Thank you very much for the lightning-speed support.