Probleminha Básico em Persistência

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.io.Serializable;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

/**
 *
 * @author Francisco
 */
@Entity
@Table(name = "USUARIO")
public class Usuario implements Serializable, Comparable<Usuario> {

    private int codigo = 0;
    public static final String PROP_CODIGO = "codigo";
    private String nome = "";
    public static final String PROP_NOME = "nome";
    private String senha;
    public static final String PROP_SENHA = "senha";
    private int nivel = 0;
    public static final String PROP_NIVEL = "nivel";
    private boolean logado = false;
    public static final String PROP_LOGADO = "logado";
    private Date dataUltimoAcesso;
    public static final String PROP_DATAULTIMOACESSO = "dataUltimoAcesso";

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "DATA_ULTIMO_ACESSO")
    public Date getDataUltimoAcesso() {
        return dataUltimoAcesso;
    }

    public void setDataUltimoAcesso(Date dataUltimoAcesso) {
        Date oldDataUltimoAcesso = this.dataUltimoAcesso;
        this.dataUltimoAcesso = dataUltimoAcesso;
        propertyChangeSupport.firePropertyChange(PROP_DATAULTIMOACESSO, oldDataUltimoAcesso, dataUltimoAcesso);
    }

    @Column(name = "LOGADO")
    public boolean isLogado() {
        return logado;
    }

    public void setLogado(boolean logado) {
        boolean oldLogado = this.logado;
        this.logado = logado;
        propertyChangeSupport.firePropertyChange(PROP_LOGADO, oldLogado, logado);
    }

    @Column(name = "NIVEL")
    public int getNivel() {
        return nivel;
    }

    public void setNivel(int nivel) {
        int oldNivel = this.nivel;
        this.nivel = nivel;
        propertyChangeSupport.firePropertyChange(PROP_NIVEL, oldNivel, nivel);
    }

    @Column(name = "SENHA")
    public String getSenha() {
        return senha;
    }

    public void setSenha(String senha) {
        String oldSenha = this.senha;
        this.senha = senha;
        propertyChangeSupport.firePropertyChange(PROP_SENHA, oldSenha, senha);
    }

    @Column(name = "NOME_REAL")
    public String getNome() {
        return nome;
    }

    public void setNome(String nome) {
        String oldNome = this.nome;
        this.nome = nome;
        propertyChangeSupport.firePropertyChange(PROP_NOME, oldNome, nome);
    }

    @Id
    @Column(name = "CODIGO")
    public int getCodigo() {
        return codigo;
    }

    public void setCodigo(int codigo) {
        int oldCodigo = this.codigo;
        this.codigo = codigo;
        propertyChangeSupport.firePropertyChange(PROP_CODIGO, oldCodigo, codigo);
    }
    private PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(this);

    public void addPropertyChangeListener(PropertyChangeListener listener) {
        propertyChangeSupport.addPropertyChangeListener(listener);
    }

    public void removePropertyChangeListener(PropertyChangeListener listener) {
        propertyChangeSupport.removePropertyChangeListener(listener);
    }

    public Usuario() {
    }

    @Override
    public int hashCode() {
        int ret = 0;
        if (this.getCodigo() > 0) {
            ret = (this.getCodigo() * 123);
        }
        return ret;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final Usuario other = (Usuario) obj;
        if (this.codigo != other.getCodigo()) {
            return false;
        }
        return true;
    }

    public int compareTo(Usuario o) {
        if (this.hashCode() < o.hashCode()) {
            return -1;
        } else if (this.hashCode() == o.hashCode()) {
            return 0;
        } else if (this.hashCode() > o.hashCode()) {
            return 1;
        } else {
            return 1;
        }
    }

    @Override
    public String toString() {
        return this.getNome();
    }
}

// Create EntityManagerFactory for persistent unit named "pu1"
// to be used in this test
emf = Persistence.createEntityManagerFactory("HorusPU");

// Persist all entities
createTransactionalEntityManager();
//System.out.println("Inserting Customer and Orders... " + testInsert());
// Create new customer
Usuario item = new Usuario();
item.setCodigo(10);
item.setNome("FRANCISCO VIEIRA");
item.setLogado(false);
// Persist the customer
em.persist(item);
closeTransactionalEntityManager();

[TopLink Info]: 2009.11.25 02:42:46.921--ServerSession(12893236)--TopLink, version: Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))
[TopLink Info]: 2009.11.25 02:42:47.656--Not able to detect platform for vendor name [Firebird]. Defaulting to [oracle.toplink.essentials.platform.database.DatabasePlatform]. The database dialect used may not match with the database you are using. Please explicitly provide a platform using property toplink.platform.class.name.
[TopLink Info]: 2009.11.25 02:42:48.140--ServerSession(12893236)--file:/C:/Projetos/Desktop/Horus/dist/Horus.jar-HorusPU login successful
Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: Object: FRANCISCO VIEIRA is not a known entity type.
	at oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl.registerNewObjectForPersist(UnitOfWorkImpl.java:3212)
	at oracle.toplink.essentials.internal.ejb.cmp3.base.EntityManagerImpl.persist(EntityManagerImpl.java:205)
	at horus.ui.ParametrosUI$1.run(ParametrosUI.java:82)
	at java.awt.event.InvocationEvent.dispatch(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)