Wordpress Multiple Site: error page redirect

Hi, I have installed the bitnami stack and configured two subdomains. Then I have modified this two subdomains to change theme in two domains. So now I have the first domain www.mastersite.com, and other two blogs for the new two domains, www.site1.com, www.site2.com.

It works!

So, I don't understand why if I try to access a wrong url (www.site2.com/wrongurl/) it does a redirect to www.mastersite.com, and not to www.site2.com.

Apache configuration is the original one (only one for the stack):

NameVirtualHost *:80

<VirtualHost *:80>
 ServerAdmin d.xxx@xxx.com
 DocumentRoot "/opt/wordpress/apps/wordpress/htdocs"
 ServerName *

<Directory "/opt/wordpress/apps/wordpress/htdocs">
   Options Indexes MultiViews +FollowSymLinks
   AllowOverride all
   Order allow,deny
   Allow from all

   RewriteEngine On
   RewriteBase /
   RewriteRule ^index\\.php$ - [L]

   # uploaded files
   RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

   RewriteCond %{REQUEST_FILENAME} -f [OR]
   RewriteCond %{REQUEST_FILENAME} -d
   RewriteRule ^ - [L]
   RewriteRule . index.php [L]
 </Directory>
</VirtualHost>

How I have to change it?

Thank you very much.