All-in-One Event Calendar on Single Page

Hello WP-community, I have the problem that All-in-One Event Calendar does not display the single post.
This must be the theme, because on other theme the permalink works.

Now my question: can I specify in my function.php or single-post.php something the single posts of All-in-One Event are displayed?
I would not like to change the theme.

Many Thanks.
Onilet