Detached entity passed to persist (Objeto não quer persistir)

import javax.persistence.Column;

import javax.persistence.Entity;

import <a href="http://javax.persistence.Id">javax.persistence.Id</a>;

import javax.persistence.ManyToOne;

import javax.persistence.PersistenceContext;

import erp.banco.Banco;

import javax.persistence.CascadeType;

import javax.persistence.FetchType;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

@PersistenceContext(unitName = “depto”)

@Entity

@SuppressWarnings(“serial”)

public class Agencia implements Serializable {

@ManyToOne(cascade = CascadeType.ALL, fetch=FetchType.EAGER)
private Banco banco;
@Id
    @GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@Column(length = 30)
private String nome;
@Column(length = 15)
private String numero;

public Agencia() {
        
}

public Banco getBanco() {
	return banco;
}


public Long getId() {
	return id;
}

public String getNome() {
	return nome;
}

public String getNumero() {
	return numero;
}

public void setBanco(final Banco banco) {
	this.banco = banco;
}

public void setId(final Long id) {
	this.id = id;
}

public void setNome(final String nome) {
	this.nome = nome;
}

public void setNumero(final String numero) {
	this.numero = numero;
}

@Override
public String toString() {
	return nome;
}

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import <a href="http://javax.persistence.Id">javax.persistence.Id</a>;

import javax.persistence.PersistenceContext;

@PersistenceContext(unitName = “depto”)

@Entity

@SuppressWarnings(“serial”)

public class Banco implements Serializable {

@Column(length = 15)
private String codigo;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@Column(length = 50)
private String nome;

public Banco() {

}

public String getCodigo() {
    return codigo;
}

public Long getId() {
    return id;
}

public String getNome() {
    return nome;
}

public void setCodigo(final String codigo) {
    this.codigo = codigo;
}

public void setId(final Long id) {
    this.id = id;
}

public void setNome(final String nome) {
    this.nome = nome;
}

@Override
public String toString() {
    return nome;
}

javax.persistence.PersistenceException: org.hibernate.PersistentObjectException: detached entity passed to persist: erp.banco.Banco

at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1377)

at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1300)

at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1306)

at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:871)