Certbot not renewing SSL certificate on AWS EC2 with CRON

Question

I use Cerbot LetsEncrypt on my AWS EC2 instance for my SSL certificate. I want to renew it automatically using CRON. I have got this in my CRON file: (using the command crontab -l)

0 0 */20 * * /usr/bin/certbot renew --quiet && /bin/systemctl reload nginx

Why my 60 days validity certificate expires and I need to renew it manually each time using :

/usr/bin/certbot renew

(nota: it works without reloading nginx)

Why I do a dry run:

/usr/bin/certbot renew --dry-run

It says that everything is ok...

What am I missing ?

Thanks.