Common Problems
From DAViCal Wiki
A number of common misconfigurations for DAViCal can occur.
mod_dav conflicts with DAViCal
Symptoms: Stuff doesn't work, particularly iCal, though the admin interface is fine.
DAViCal needs to handle all DAV activity for the calendar paths so if you have to have mod_dav installed within the virtual host used for DAViCal you need to make sure that mod_dav is disabled for the subset of paths covering where DAViCal is installed.
Text after PHP closure in configuration file
Symptoms: Prompted to log in for each page in the admin interface.
If you have extra characters after the ?> at the end of your DAViCal configuration file you need to remove them. While you're at it, remove the ?> as well so it doesn't happen again! The problem is that this causes the output to the browser to be started before DAViCal has sent it's session cookie. So the browser never receives the session cookie, and never actually manages to log in for more than the single page.

