can any body tell me why following warnings are coming when i am deploying CMP EJBs

ERROR

Bean : ArticleEJB
Section: 9.2.2
Warning: The entity bean class must not be defined as abstract.

15:28:36,024 INFO [EJBDeployer]
Bean : ArticleEJB
Section: 9.4.7.1
Warning: The primkey-field element must name a public field in the bean implementation class.


I will appreciate for quick response.

Thanks
KPK