Enabling calendaring

Hi

I have installed the latest version of Sqwemail from source 
(--prefix=/usr/local/sqwebmail) and all runs smoothly.
But now I wanted to enable calendaring. I created the file calendarmode 
(-rw-r--r--), containing the word local, in the directory 
/usr/local/sqwebmail/share, but nothing changed, even after rebooting 
the server.
What have I missed?

Thanks

Rudi