Caldav error executing event job

I just got started with the caldav.io / command bindings. I added an event with description:

BEGIN:Item:ON

The log looks good so far, until the very second it is supposed to start:

2016-03-29 22:35:00.019 [INFO ] [o.caldav.internal.job.EventJob] - event END for: g87skir0ro6(Test-Item an@29.03.2016/22:35-29.03.2016/22:40)
2016-03-29 22:35:00.021 [ERROR] [o.caldav.internal.job.EventJob] - error executing event job
org.quartz.JobExecutionException: cannot get event-container for config: mycal and eventId: g87skir0ro6
        at org.openhab.io.caldav.internal.job.EventJob.execute(EventJob.java:37) ~[na:na]
        at org.quartz.core.JobRunShell.run(JobRunShell.java:213) [quartz-all-2.1.7.jar:na]
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:557) [quartz-all-2.1.7.jar:na]

Has anyone seen this or got some hints on where to start searching?

Did you add your event in the subject field or in the message body?

Correct = message body.

Yip, I did. Rechecked with all combinations I found in the Forums. :worried: