Using Hibernate+Derby in Netbeans module

Question

Hi people,

I am developing a Netbeans app/module and I like to use a Derby database in it. I created a separate library handling Derby communication (working well). Then I like to use this library in Netbeans module so I imported it as a wrapped library module into my Netbeans app. When compiling I get following warning:

Warning: xyz.zzyDAO cannot access org.hibernate.Session

and the session is not initialized (set as null). I don't know how to make it works. Can you please help me?