[EventCalendar] EC 3.1pre14/15: Date-Inteface doesn't work

[Ralf Thees]

I updated from EC 3.1pre13 to pre15. But now the date-interface at the
post-page doesn't work anymore, it isn't displayed at all. In EC
3.1pre13 it worked fine. I've testet it with the pre14 - there it also
doesn't work.
What's wrong? Anyone with the same problem?

Greetings, Ralf ...