Various server whit only one IP and Port for external connection

[Andrea Davoli <adavoli@xxxxxxxxxxxxxxxx>]

Hi, i have a DMZ newtork whit 3 server apache on 3 different subdomain but only 1 IP adress. I wont all server answer on standard http port so, my idea is build a main server whit virtual host and mod_proxy for listen on MyIP, port 80 and proxy request on other server...

I have do this apache conf;

<VirtualHost *:80>
        ServerAlias mydomain.domain.com
        ProxyRequests Off
        <Proxy />
                Order deny,allow

                Allow from all
                ProxyPass http://192.168.1.2/
                ProxyPassReverse http://192.168.1.2/
        </Proxy>

</VirtualHost>
<VirtualHost *:80>
        ServerAlias sub2.domain.com
        ProxyRequests Off
        <Proxy />
                Order deny,allow
                Allow from all
                ProxyPass http://192.168.1.3/
                ProxyPassReverse http://192.168.1.3/
        </Proxy>
</VirtualHost>

<VirtualHost *:80>
        ProxyRequests Off
        ServerAlias domain.domain2.org
        ServerAlias subdomanin.domain.com

        DocumentRoot /var/www
        <Directory /var/www/>
                Options Indexes FollowSymLinks MultiViews
                AllowOverride None
                Order allow,deny
                allow from all

        </Directory>


And work fine but, if i try do use my main server as openproxy he dont anwer whit "forbidden" but only whit "not found" and send my request on other DMZ server

So, if i try to get some domain "www.apache.org" he send request to 192.168.1.2.. this sever answer "not found 404" and my main server send it to me...
Where is the error on this config? 

What can i do for use apache whit subdomain proxy buy only for this subdomain (and not for other request?)