No vhost found http challenge

I created the folders:

sites-available
sites-enable

Create the vhost file in folder sites-available with content:

<VirtualHost *:80>
ServerName apache.labo.jacquemin.eu
ServerAdmin herve@jacquemin.eu
DocumentRoot /var/www/apache.labo.jacquemin.eu/public_html
ErrorLog /var/www/apache.labo.jacquemin.eu/error.log
CustomLog /var/www/apache.labo.jacquemin.eu/requests.log combined

restart the server but nothing seems to work.

The apachectl -S command show nothing.