protected virtual void addButton_Click(object sender, EventArgs e) { if (fieldsOK()) { if (businessControl.findPersonByDni(dnitextBox.Text) != null) { MessageBox.Show("Person with this DNI already exists", "Error"); } else { Person p = new Person(dnitextBox.Text, nametextBox.Text, addresstextBox.Text, citytextBox.Text, postalcodetextBox.Text, driverLicensedateTimePicker.Value); businessControl.addPerson(p); newReservationForm.addPersonFormConfirmed(p.dni); } } else { MessageBox.Show("Missing Fields", "Error"); } }