Hello Bernd,
Based on your error message it is most likely due to permission issue when you try to install easy blog.
It appears that when run the SQL code in order to create table to install the easy blog component we encountered this error. This is due to lack of permission to run the sql code on the backend.
But you may try and run the sql code yourself & install the component by following this steps:
1. Copy all the sql code from the attached sql file given. Replace the
#_ with your table prefix.
2. Paste the sql code in your myPHPadmin and run it.
3. Unzip your easyblog installer file if you have not unzip (skip this part if you already unzip it)
4. go to your easyblog installer file > admin > look for this file install.mysql.utf8.sql as shown in this screenshot
http://screencast.com/t/4q4vXlIA
5. once you already accessed the install.mysql.utf8.sql, remove all the sql codes then save it then zipped the installer file again
6. Go to your backend > extension manager > upload the recently zipped installer file
Hope this solves your problem