I found out myself:

> C:\>"C:\Programme\Firebird2\bin\gbak.exe" -t -v -z
> -service elias/3052:service_mgr
> -user "SYSDBA" -password "masterkey"
> "elias/3052:C:\Programme\Firebird2\security2.fdb" [...]

^^^^^^^^^^^
This is unnecessary (and obviously wrong) when using the service
manager.


Regards

Stefan