I am trying to use the Calendar plugin for roundcube mail, but the logs show that when it tries to contact the CalDav backend (baikal server), the calendar plugin is not sending authentication headers. I have been in contact with the calendar plugin team tech support, and they claim it must be a configuration problem with my server or PHP. They did say this is a known issue when running with FastCGI, however phpinfo() on my server says the Server API is "Apache 2.0 Handler", and not FastCGI. I know nothing about PHP (I'm a python guy). What might I need to change to get the PHP script to send the authentication headers?