can install drupal core site (for multisites) under websites basedir, e.g. /var/www?
i have two sites, mysite-1.com and mysite-2.com and want to install them as drupal multisites (shared the same drupal codebase) in the same server, i.e. ispconfig 3 hosting server, but i want to install the shared drupal codebase under /var/www, the websites basedir, not under any of mysite-1.com or mysite-2.com directories. but when install the drupal core site (mysite-1.com/install.php), the site couldn't be installed properly, e.g. can't browse to the drupal site after installation, while if install the drupal core site under mysite-1.com or mysite-2.com directories, then it is ok.
may i ask why that? how can i make it working when install the drupal core site under the websites basedir /var/www?