How to make 3 SelectOneMenu nested?

I'm creating a page that has to have 3 SelectOneMenu of primefaces. In the first one I will load a center (of the university), the second will carry a edital and the third would load the disciplines of this edital.

The first SelectOneMenu works, when change of option it loads only the edicts of that option. But when I change the option of the second SelectOneMenu it no longer calls the method. Why is not he calling the method? What is wrong? Here are the codes:

deferirInscricoes.xhtml

<h:form id="formInscricoes">

    <p:selectOneMenu id="selectCentro" value="#{inscricaoBean.centroSelecionado}" converter = "centroConverter">
        <f:selectItem itemValue="#{null}" itemLabel="- Selecione um Centro -" />
        <f:selectItems value="#{inscricaoBean.listaCentros}" var="centro" itemValue="#{centro}" itemLabel="#{centro.nome}"/>
        <p:ajax event="change" process="@this" listener="#{inscricaoBean.carregaEditais}" update="selectEdital" />
    </p:selectOneMenu>

    <p:selectOneMenu id="selectEdital" value="#{inscricaoBean.editalSelecionado}" converter = "editalConverter">
        <f:selectItem itemValue="#{null}" itemLabel="- Selecione um Edital -" />
        <f:selectItems value="#{inscricaoBean.listaEditaisPorCentro}" var="edital" itemValue="#{edital}" itemLabel="#{edital.titulo}"/>
        <p:ajax event="change" process="@this" listener="#{inscricaoBean.carregaDisciplinas}" update="selectDisciplinas" />
    </p:selectOneMenu>

    <p:selectOneMenu id="selectDisciplinas" value="#{inscricaoBean.disciplinaSelecionada}" converter = "disciplinaConverter">
        <f:selectItem itemValue="#{null}" itemLabel="- Selecione uma Disciplina -" />
        <f:selectItem itemValue="#{null}" itemLabel="- Teste -" />
        <f:selectItems value="#{inscricaoBean.listaDisciplinaPorEdital}" var="disciplina" itemValue="#{disciplina}" itemLabel="#{disciplina.nome}"/>
    </p:selectOneMenu>  
 <h:form>

inscriptionBean.java

private List<Centro> listaCentros;
private List<Edital> listaEditaisPorCentro;
private List<Disciplina> listaDisciplinaPorEdital;
CentroDAO centroDAO = new CentroDAO();
EditalDAO editalDAO = new EditalDAO();
DisciplinaDAO disciplinaDAO = new DisciplinaDAO();
private Centro centroSelecionado;
private Edital editalSelecionado;
private Disciplina disciplinaSelecionada;

// Todos os getters e setters acima foram criado no padrão.

public void carregaEditais() {
    System.out.println("Editais carregados.");
    listaEditaisPorCentro = editalDAO.getListaEdital(centroSelecionado);
}

public void carregaDisciplinas() {
    System.out.println("Disciplinas carregadas.");
    listaDisciplinaPorEdital = disciplinasDAO.getListaDisciplinaPorEdital(edital);
}

}

CentroConverter.java

@FacesConverter("centroConverter")
public class centroConverter implements Converter {

    public Object getAsObject(FacesContext fc, UIComponent uic, String value) {
        if(value != null && value.trim().length() > 0) {
            try {
                CentroDAO centroDAO = new CentroDAO();
                Integer id = Integer.parseInt(value);
                Centro centro = centroDAO.getCentro(id);
                return centro;

            } catch(Exception e) {
                System.out.println("Problema no centroConverter.!");
                throw new ConverterException(new FacesMessage(FacesMessage.SEVERITY_ERROR, "Erro de conversão", "Not a valid theme."));
            }
        }
        else {
            return null;
        }
    }

    public String getAsString(FacesContext fc, UIComponent uic, Object object) {
        if(object != null) {
            Centro c = new Centro();
            c = (Centro) object;
            return ""+c.getIdCentro();
        }
        else {
            return null;
        }
    }   
}     

EditalConverter.java

@FacesConverter("editalConverter")
public class editalConverter implements Converter {

    public Object getAsObject(FacesContext fc, UIComponent uic, String value) {
        if(value != null && value.trim().length() > 0) {
            try {
                EditalDAO editalDAO = new EditalDAO();
                Integer id = Integer.parseInt(value);
                Edital edital = editalDAO.getEdital(id);
                return edital;

            } catch(Exception e) {
                System.out.println("Problema no editalConverter.!");
                throw new ConverterException(new FacesMessage(FacesMessage.SEVERITY_ERROR, "Erro de conversão", "Not a valid theme."));
            }
        }
        else {
            return null;
        }
    }

    public String getAsString(FacesContext fc, UIComponent uic, Object object) {
        if(object != null) {
            Edital e = new  Edital();
            e = (Edital) object;
            return ""+e.getIdEdital();
        }
        else {
            return null;
        }
    }   
}     

DisciplineConverter.java

@FacesConverter("disciplinaConverter")
public class disciplinaConverter implements Converter {

    public Object getAsObject(FacesContext fc, UIComponent uic, String value) {
        if(value != null && value.trim().length() > 0) {
            try {
                DisciplinaDAO disciplinaDAO = new DisciplinaDAO();
                Integer id = Integer.parseInt(value);
                Disciplina disciplina = disciplinaDAO.getDisciplina(id);
                return disciplina;

            } catch(Exception e) {
                System.out.println("Problema no disciplinaConverter.!");
                throw new ConverterException(new FacesMessage(FacesMessage.SEVERITY_ERROR, "Erro de conversão", "Not a valid theme."));
            }
        }
        else {
            return null;
        }
    }

    public String getAsString(FacesContext fc, UIComponent uic, Object object) {
        if(object != null) {
            Disciplina d = new Disciplina();
            d = (Disciplina) object;
            return ""+d.getIdDisciplina();
        }
        else {
            return null;
        }
    }   
}     

The first method it calls, loads the list. But the second does not. I put a print just to test, but the method is not being called.