If you have installed the esyndicat directory in the root directory of your site and also have several other websites running as subdomains under the same url then you will have all the chances that the subdomains to not work. You will receive a 500 Internal Error.
In order to fix this here is the solution:
Under each of your subfolder that hosts a new site, write the following in the .htaccess file: (replace index.php file with your own index file name and extension.)

Code:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

ErrorDocument 500 /dir/500.htm
ErrorDocument 404 /dir/404.htm
ErrorDocument 403 /dir/403.htm
ErrorDocument 401 /dir/401.htm