[SOLVED] Stripe module on Prestashop 1.5.6.1 : credit card input widget disabled

I added stripe module in Prestashop 1.5.6.1 to integrate my webshop https://store.creasol.it with a credit card payment that is cheaper in respect to Paypal.
0.25€ + 1.4% fee for transactions from Europe
0.25€ + 2.9% fee for transactions from Extra-UE
The problem is that some input fields were disabled, so it was impossible for the customer to specify the credit card number, expiration and CVV.
To solve this problem I had to set, in Prestashop -> Advanced Parameters -> Performance ,  
Smart cache for JavaScript: Keep JavaScript as original
because when  
Smart cache for JavaScript was set to Use CCC for JavaScript
some input fields disapper.