EclipseLink problem

 Hi all!..

Im experience a problem when running my web app that uses JPA,

java.lang.IllegalArgumentException: No [EntityType] was found for the key class [xxxx.yyyy] in the Metamodel - please verify that the [Entity] class was referenced in persistence.xml using a specific <class>xxxx-.yyyy</class> property or a global <exclude-unlisted-classes>false</exclude-unlisted-classes> element.> 

I have tried restarting the weblogic server, but it couldnt solve my problem. My persistence,xml its ok. I have read and seems to be an eclipseLink bug.

Any Ideas?? I appreciate any help.

Denisse.