Setup of firebird database access


I installed firebird 3.0 on my server and installed the examples.fdb database. Then I added the service “firebird” and on the config page I used:

host: localhost
port: 3050
database: examples.fdb (this is defined as alias in fb, but I also tried full path)
username: SYSDBA
password: the-current-passwort for SYSDBA
charset: utf8
allow upsert: aktivated (but I also tried deactivated)
Data cache retrival: I tried both acivated and deactivated
chache time: 1

when ever I try to access data, I receive the message, that user and password are not setup. But this is not true, because these data work when I access the database through ssh and there isql-fb. So I assume that the system does not find the database, because it I change the database to any entry (like: test), I receive exactly the same error message and again I rechecked user data and password many times, they are correct. How do I have to specify the database path? as an absolute path? Are there any settings for owner of group ? I even created a new path which I allowed everybody to have read and write access and I copied the database to that new directory. But still it does not work. Any idea, what I do wrong?