Erro relatório

package relatorios;
import java.sql.ResultSet;
import java.util.*;
import javax.swing.JOptionPane;
import java.lang.*;
import java.net.URL;  
import java.util.HashMap;

import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.view.JasperViewer; 


import utilitarios.conexao;

public class relPatrimonio {


    conexao con_patrimonio = new conexao();


public relPatrimonio() {
  try
  {
      con_patrimonio.conecta();
      con_patrimonio.executeSQL("SELECT * from tb_patrimonio");
      JRResultSetDataSource jrRS = new JRResultSetDataSource(con_patrimonio.resultset);
      JasperPrint jasperPrint = JasperFillManager.fillReport("src/relatorios/relPatrimonio.jasper", new HashMap(),jrRS); // o erro esta nesta linha
      JasperViewer.viewReport(jasperPrint,false);
  } catch (Exception erro){
             JOptionPane.showMessageDialog(null,"deu erro ="+erro);
   }
}

  public static void main (String args[])
  {
    new relPatrimonio();
  }

    private static class JRResultSetDataSource {

        public JRResultSetDataSource(ResultSet resultset) {
        }
    }

    }