Error in ADF Application

Hi,

I have completed the development of an Oracle ADF Application. It consists of EJBs, Session  bean and JSP pages using the data control from the session bean. The application is working perfectly  in my jdeveloper (version10.1.3.3.0). However, after I deploy this to our production server, I get the below error when I try to do some action.

1.JBO-29000: Unexpected exception caught: javax.ejb.EJBException, msg=Exception [TOPLINK-28013] (Oracle TopLink Essentials - 2006.8 (Build 060829)): oracle.toplink.essentials.exceptions.EntityManagerSetupException Exception Description: Attempted to deploy PersistenceUnit [Model] for which predeploy method either had not called or had failed; nested exception is: javax.persistence.PersistenceException: Exception [TOPLINK-28013] (Oracle TopLink Essentials - 2006.8 (Build 060829)): oracle.toplink.essentials.exceptions.EntityManagerSetupException Exception Description: Attempted to deploy PersistenceUnit [Model] for which predeploy method either had not called or had failed
2.Exception [TOPLINK-28013] (Oracle TopLink Essentials - 2006.8 (Build 060829)): oracle.toplink.essentials.exceptions.EntityManagerSetupException Exception Description: Attempted to deploy PersistenceUnit [Model] for which predeploy method either had not called or had failed; nested exception is: javax.persistence.PersistenceException: Exception [TOPLINK-28013] (Oracle TopLink Essentials - 2006.8 (Build 060829)): oracle.toplink.essentials.exceptions.EntityManagerSetupException Exception Description: Attempted to deploy PersistenceUnit [Model] for which predeploy method either had not called or had failed.

This is not the first time I have deployed ADF apps. It used to work fine for me in the past. I am not sure of the issue with this application.

Kindly assist.