LetsEncrypt don't want generate for a domain

Hi,
On my server I have different website, but for one domain I have a problem to generate the certificate.
So I did Sites->My web site->Checked SSL & Let's encrypt SSL checkboxes, waited for applying changes to complete, after that when I control the SSL tab it was empty and both checkboxes where unchecked again.
When I see the log /var/log/letsencrypt, it's no message for this domain.
NSlookup is ok
Then I don't understand the problem for this domain
Have you a idea ?
Thank you very a lot

 

Follow these instructions: https://www.howtoforge.com/community/threads/lets-encrypt-error-faq.74179/

When using Let's Encrypt certificate the boxes in SSL tab are always empty.

 

Thanks, I have see this FAQ, but I don't find the solution because for the all other domain is ok, just not for this. And I don't find log for this domain to define the problem.