Hibernate version: Hibernate 3.0

Full stack trace of any exception that occurs:

Deployment failed: See base exception for details.
Resolution:
See base exception for details.
Base Exception:
com.evermind.server.rmi.OrionRemoteException
Class not found: org.hibernate.exception.GenericJDBCException; nested exception is:
java.lang.ClassNotFoundException: org.hibernate.exception.GenericJDBCException. Class not found: org.hibernate.exception.GenericJDBCException; nested exception is:
java.lang.ClassNotFoundException: org.hibernate.exception.GenericJDBCException

Name and version of the database you are using:

Oracle 10g

I am trying to deploy my application to OC4J and am getting the exception mentioned above.

Does anybody have an idea why this happens? Can anybody please suggest where else can I look for a solution of this problem.