Problem involving permalinks and apache

I have my wordpress in htdocs folder inside apache.
To be able to access, I defined virtual host in vhosts in apache this way:

<VirtualHost *:80>
        ServerAdmin [email protected]
        DocumentRoot "/xxx/xxxx/htdocs/"
        ServerName domainname.com
        ErrorLog logs/domainname-error_log
        CustomLog logs/domainname-access_log common
</VirtualHost>

After restarting apache, I can access to my wordpress, but if I define any permalink distinct than default one, I’m not able to acces any page except homem, displays a Not Found message. The .htaccess file is correctly created in htdocs folder at the same level as wp-admin.

I tried the following, I removed .htaccess file and I defined the rewrite rules in the virtual host. So. the virtual host looks like this now:

<VirtualHost *:80>
        ServerAdmin [email protected]
        DocumentRoot "/xxx/xxxx/htdocs/"
        ServerName domainname.com
        ErrorLog logs/domainname-error_log
        CustomLog logs/domainname-access_log common

        RewriteEngine On
        RewriteRule ^index\.php$ - [L]
        RewriteCond %{REQUEST_FILENAME} !-f
        RewriteCond %{REQUEST_FILENAME} !-d
        RewriteRule . /index.php [L]
</VirtualHost>

After restarting apache, permalinks work like a charm, but now I cannot access to the administration dashboard page, redirecting always to the home page.

How can I solve this problem?, I’ve checked through a lot of entries but none of them talks about virtual host definitions.

Thank you