undefined constant FULLCALENDAR_PATH

Should be fixed now in latest dev release.

When will you fix it in the rc version. I seldom use development version, so wait for recommended version to be updated...Thanks

I still get this Error after updating to latest dev version.

"Warning: file_get_contents(/abenteuerfarm/sites/all/libraries/fullcalendar/fullcalendar.min.js): failed to open stream: No such file or directory in fullcalendar_get_version() (line 386 of /var/www/vhosts/demohub.de/httpdocs/abenteuerfarm/sites/all/modules/fullcalendar/fullcalendar.module)."

You can see my calender here: www.demohub.de/abenteuerfarm/kalender-v2
I set the directory in the option to "/abenteuerfarm/sites/all/libraries/fullcalendar"

And that is how the directory looks like:
/abenteuerfarm/sites/all/libraries/fullcalendar/fullcalendar.css
/abenteuerfarm/sites/all/libraries/fullcalendar/fullcalendar.js
/abenteuerfarm/sites/all/libraries/fullcalendar/fullcalendar.min.js
/abenteuerfarm/sites/all/libraries/fullcalendar/fullcalendar.print.css
/abenteuerfarm/sites/all/libraries/fullcalendar/gcal.js

Any idea about that?

The directory option should just be sites/all/libraries/fullcalendar, no site name or leading slash