Wordpress oEmbed dont work with Podcast Post

my Podcast is on a Subdomain podcast.fotoglut.de
Now i would embend via the Wordpress Embed Funktion a Podcast Post to an other Post related to that Podcast on the “Main” Domain (fotoglut.de).
But all i get is the URL.

If i try it with an other Post (no Podcast), it works.
Any Idea?