Problem when inserting data from a java application to a MYSQL database

I am trying to make a record from a java application but when I clicked the accept button it does not save the data in the DB (Mysql) I am using the IDE Eclipse here I leave the code where I do the registration.

Connection con = null;

        try {

        con = getConection();
        ps=con.prepareStatement("INSERT INTO alumno (num_control,Nombre,fecha_inicio,fecha_termino) VALUES (?,?,?,?)");         
        ps.setString(1,RegistroAlumno.numc2.getText());         
        ps.setString(2,RegistroAlumno.nom2.getText());          
        ps.setDate(3,Date.valueOf(RegistroAlumno.fecha_inicio2.getText()));
        ps.setDate(4,Date.valueOf(RegistroAlumno.numc2.getText()));


        int res = ps.executeUpdate();
        System.out.println("Res= "+res);
        if(res > 0 ) {

        JOptionPane.showMessageDialog(null," ! Registro exitoso ! ");   
        RegistroAlumno.LimpiarCajasTextos();

        }else {

            JOptionPane.showMessageDialog(null," Registro fallido, verifique su conexion a la Base de Datos ... "); 
            RegistroAlumno.LimpiarCajasTextos();

        }

        con.close();

        }catch(Exception e) {

        }