Ok, then I assume you are using a proxy or load balancer befor the actual install that handles https. Is that correct?
If so, you should change the configuration of the proxy server of the loadbalancer to make sure the follwing header is set to https:
HTTP_X_FORWARDED_PROTO
I use an apache reverse proxy and in my virtual host file I have:
ProxyRequests Off
ProxyPreserveHost On
ProxyPass "/" "
xerte-template.xxxxx/
" disablereuse=On
ProxyPassReverse "/" "
xerte-template.xxxxx/
"
RequestHeader set X-Forwarded-Proto "https"
If that is not pssoible or inconvenient, copy the file reverse_proxy_conf.php.dist to reverse_proxy_conf.php and make sure that the column site_url in the sitedetails table has the correct value. I would not edit config.php and add th eparameter there, because that file might be overwritten in a future update of the installation.
Tom