"Step 4: Enabling the Network" Failed!!!

I installed a clean WordPress site on apache2/ubuntu in order to make a Multisite WordPress.
I followed the Codex “Create a Network” guide. At the end of step 4 I login again in the site but the section “My Site” don’t appear ?? I can′t go ahead with the guide!!!
The site looks like multisite isn’t enabled.
.htaccess content:
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]

Last part of wp-config.php

/* Multisite */
define( ‘WP_ALLOW_MULTISITE’, true );
define(‘MULTISITE’, true);
define(‘SUBDOMAIN_INSTALL’, true);
define(‘DOMAIN_CURRENT_SITE’, ‘blog.cuvenpetrol.cu’);
define(‘PATH_CURRENT_SITE’, ‘/’);
define(‘SITE_ID_CURRENT_SITE’, 1);
define(‘BLOG_ID_CURRENT_SITE’, 1);

I configured WordPress Network with subdomain and subdirectory options and the problem is the same.
Help Please!!!