Shutdown Interbase Database from Delphi

Question

Using the TIBConfigService I'm attempting to shutdown an Interbase database using its ShutdownDatabase method like so:

ibConfig.ShutdownDatabase(Forced, 0);

This ends up with an error, "Invalid Service Handle".

Setting the Active property on the control is successful and other methods on the TIBConfigService such as SweepDatabase work as expected.

How can I resolve the "Invalid Service Handle" error?