> Could you provide me any tip about it?

Execute this before connecting with Hibernate:

CREATE GENERATOR HIBERNATE_SEQUENCE;

This is needed only when id generator type is set to "native".

> Oh dear, how can I do that about the password without changing it?

No chance, except fixing JayBird. But we are almost ready with JayBird 2.0
beta, so I'm not yet convinced that JayBird 1.5.6 is needed.

Roman