Broken

Could you send me a link of your page?

https://semseo.abakus-internet-marketing.de/bilder/semseo-2014-konferenz/

Have you tried to disable any other plugins that you use?

I did, but does not have any effect.

Could you try to update your permalinks.
You can do this in the admin page > Settings > Permalinks
There just press the button save Changes.

done.

You’re welcome

…but it’s still not working …

Clear your cache. If i check the link and click on slideshow it works now.

confirmed, slideshow is working on your website.

How about browsing, starting with the first image …?

Start new questions in a new thread please.