Deploy projeto erro scope of the module called

estou fazendo um deploy do meu projeto, porem esta dando o erro abaixo: cannot Deploy projectejb deploy is failing=Error occurred during deployment: Exception while preparing the app : Could not resolve a persistence unit corresponding to the persistence-context-ref-name [br.com.caelum.livraria.dao.AutorDao/manager] in the scope of the module called [projectejb]. Please verify your application.. Please see server.log for more details.

obs: estou utilizando, eclipse, ejb e glassfish. alguem jah passou por isso ?

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<?xml version="1.0" encoding="UTF-8"?> org.eclipse.persistence.jpa.PersistenceProvider false

@Stateless public class AutorDao { @PersistenceContext(unitName="myPU") private EntityManager manager; public void salva(Autor autor) { this.manager.merge(autor); }