When defining a SSL virtual host this way:
<VirtualHost *:443> DocumentRoot "/your/document/root" ServerName your.domain.name </VirtualHost>
HTTPS environment variable is not set, hence, for example, the
$_SERVER['HTTPS'] is not set under PHP, leading to errors, especially for a service which is only available through HTTPS.
You normally had to add
SSLOptions +StdEnvVars entry in the Apache configuration file, but, due to some restrictions concerning SSL, you have apparently also to set most of the SSL related directives.