Problems with DataExporter

I can not export data from my table, even following the example of Primefaces Showcase . I use version 5.0.

<h:commandLink><p:graphicImagelibrary="img" name="xlsx.png" width="32" title="Exportar para Excel"/>
            <p:dataExporter type="xlsx" target="dataTable" fileName="Relatorio" />
        </h:commandLink>

        <h:commandLink>
            <p:graphicImage library="img" name="pdf.png" width="37" title="Exportar para PDF"/>
            <p:dataExporter type="pdf" target="dataTable" fileName="Relatorio"/>
        </h:commandLink>

        <p:dataTable var="r" value="#{controleBean.reservatorios}"
            paginator="true" rows="30" id="dataTable"
            emptyMessage="Nenhum Reservatorio Cadastrado"
            paginatorPosition="bottom" 
            selection="#{controleBean.reservatorioSelecao}"
            selectionMode="single" rowKey="#{r.idReservatorio}"> 

            <p:ajax event="rowSelect"
                update=":form:btnEditar :form:btnExcluir" />
            <p:ajax event="rowUnselect"
                update=":form:btnEditar :form:btnExcluir" />

            <p:column headerText="Nome">
                <h:outputText value="#{r.nomeReservatorio}" />
            </p:column>

            <p:column headerText="Capacidade (Lt)">
                <h:outputText value="#{r.capacidadeReservatorio}" />
            </p:column>

            <p:column headerText="Tipo">
                <h:outputText value="#{r.tipoReservatorio}" />
            </p:column>

            <p:column headerText="Observação">
                <h:outputText value="#{r.obsReservatorio}" />
            </p:column>
        </p:dataTable>