Multi-site install – original site is fine, 500 error on the new subdomain

Hello,
I’ve got a working site at http://lesbeauxebooks.com/ which I’d like to duplicate and translate into English on a subdomain, and then map a new domain to it. I plan to use a multi-site install with Multi-Lingual Press.

I’ve installed the WP network and the original site works fine still but when i try to access the new subdomain http://en.lesbeauxebooks.com/ or the dashboard at http://en.lesbeauxebooks.com/wp-admin I get a 500 error “The domain / subdomain has not been found. Error 500.”

I’ve checked the DNS, the wildcard subdomain exists. I don’t have access to the server to verify / create it myself but as the hosting offer I’m using specifies “unlimited subdomains” logically it’s in place there as well, yes ?

I created the subdomain “en” in WordPress and it does appear in the WP network admin dashboard.

In the wp-config.php I’ve added this code :

/* Multisite */

define('WP_ALLOW_MULTISITE', true );
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', true);
define('DOMAIN_CURRENT_SITE', 'lesbeauxebooks.com');
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);

/* That's all, stop editing! Happy blogging. */

And here is the modified htaccess file :

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

</IfModule>

# END WordPress

Any help would be greatly appreciated! I’m completely at a loss and my head is spinning after reading through about a gazillion different forum topics and blog posts. I called my hosting company in case they had an idea but they have been no help. :/