Translate Validation Constraint Messages on Symfony - symfony

Question

In order to have error messages in different languages, I am following the instructions under this link:
https://symfony.com/doc/current/validation/translations.html
I made the validator files with yaml:
For instance:
# translations/validators.en.yml
author.name.not_blank: Please enter the name of the author.
Notice: I tried the extensions yaml and yml
And in src/entity/Data.php
/**
* #var string
*#Assert\NotBlank(message="author.name.not_blank")
*/
private $author;
I just get the message "author.name.not_blank" instead of "Please enter the name of the author."
I cleared the cache like this:
https://symfony.com/doc/2.7/console/usage.html
php app/console cache:clear --env=prod
I get the temporary message on the terminal "Clearing the cache for the prod environment with debug false"
So my questions are: Am I doing something wrong in clearing the cache?
I am using Symfony 2.7
Is there something I am missing ?
By the way, all other translations from files such as
translations/messages.en.yml
are functionning perfectly well.
Thank you very much!

Answer 1

I see your code is fine:
now you can check additional stuff:
app/config:
translator: { fallbacks: ["%locale%"] }
and be sure which environment are you in.
instead of
php app/console cache:clear --env=prod
try
php app/console cache:clear
hope this will helps.