IReport com Hibernate

package tela;

import dao.DaoRah;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.JasperPrint;
import net.sf.jasperreports.engine.data.JRBeanCollectionDataSource;
import net.sf.jasperreports.view.JasperViewer;

public class GeraRelatorio {

    JasperPrint jpt = null;
    public void geraRelatorio(Collection data) throws JRException, Exception {
        Map parameters = new HashMap();
        jpt = JasperFillManager.fillReport("RAH.jasper", parameters, new JRBeanCollectionDataSource(data));
        JasperViewer.viewReport(jpt, false);
    }

    public static void main(String args[]) {
        DaoRah dao = new DaoRah();
        try {
            new GeraRelatorio().geraRelatorio(dao.listarTodos());
        } catch (JRException ex) {
            Logger.getLogger(GeraRelatorio.class.getName()).log(Level.SEVERE, null, ex);
        } catch (Exception ex) {
            Logger.getLogger(GeraRelatorio.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

net.sf.jasperreports.engine.JRException: Error retrieving field value from bean : 
        at net.sf.jasperreports.engine.data.JRAbstractBeanDataSource.getBeanProperty(JRAbstractBeanDataSource.java:123)
        at net.sf.jasperreports.engine.data.JRAbstractBeanDataSource.getFieldValue(JRAbstractBeanDataSource.java:96)
        at net.sf.jasperreports.engine.data.JRBeanCollectionDataSource.getFieldValue(JRBeanCollectionDataSource.java:100)
        at net.sf.jasperreports.engine.fill.JRFillDataset.setOldValues(JRFillDataset.java:823)
        at net.sf.jasperreports.engine.fill.JRFillDataset.next(JRFillDataset.java:787)
        at net.sf.jasperreports.engine.fill.JRBaseFiller.next(JRBaseFiller.java:1478)
        at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:125)
        at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:942)
        at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:860)
        at net.sf.jasperreports.engine.fill.JRFiller.fillReport(JRFiller.java:84)
        at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:624)
        at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:540)
        at tela.GeraRelatorio.geraRelatorio(GeraRelatorio.java:20)
        at tela.GeraRelatorio.main(GeraRelatorio.java:27)
Caused by: java.lang.NoSuchMethodException: Unknown property '' on class 'class entidades.Rah'
        at org.apache.commons.beanutils.PropertyUtilsBean.getSimpleProperty(PropertyUtilsBean.java:1313)
        at org.apache.commons.beanutils.PropertyUtilsBean.getNestedProperty(PropertyUtilsBean.java:762)
        at org.apache.commons.beanutils.PropertyUtilsBean.getProperty(PropertyUtilsBean.java:837)
        at org.apache.commons.beanutils.PropertyUtils.getProperty(PropertyUtils.java:426)
        at net.sf.jasperreports.engine.data.JRAbstractBeanDataSource.getBeanProperty(JRAbstractBeanDataSource.java:111)
        ... 13 more