Changing avatar in Blogger info doesn't work

I'm trying to upload an individual image for my user name, but it's not working.

This is what I tried:
- In the backend, go to Bloggers.
- Pick blogger name from list, click on "Blogger info".
- The forth item on this page is Avatar. It shows the gray standard blogger picture.
- Click on "Choose file" (I've set the language to German, here it says "Datei auswählen" ), and pick an image file from my hard drive ( I tried several different files in jpg and png, file size around 20-50 KB.)
- The file name then shows next to the "Choose file" button (the image is still the gray standard image).
- When I click on save, I get an empty white page and this URL tries to load:
http://www.my-website.de/administrator/index.php?option=com_easyblog&c=user
- When I check, the new image hasn't been used, it's still the gray standard blogger picture.

Under Layout/Avatars, the settings are as follows:
- Enable avatars: yes
- Modify author's name and avatar links: no
- Avatar integrations: default
- Enable category avatar: yes
- Enable team blog avatars: no

I'm not sure what I'm doing wrong? Can you please help?