Working ISPConfig 3: installed nginx in front of Apache - client documentroot directories problem

Hi

As title says - I have an ISPConfig 3 system up and running, all well with sites configured and running.
Now, I want to install NGinx in front of the Apache and it works, however, the domain DocumentRoot directory specified in ISPConfig no longer in use. The system goes to /var/www/html instead of the "/var/www/clients/clientX/web1/web" - X being the client number

It's like the ISPConfig configuration is no longer utilized

How can I solve it? is it solveable?
I just want NGinx to deliver the images/js/css files

 

anyone? would really like to know how to configure Apache + NginX