Problem with radio validation

Hi,
thanks for this beautiful joomla component.
I have a problem.
I need to validate a radio button: I have 2 radio button "si" and "no" . I need that the email will send only if a user select "SI", if user select "NO" it will receive an error message.
Actually the email will be sent in all case.
The page is http://www.paradisohotel.eu/index.php?option=com_chronocontact&chronoformname=Prenotazione

My code is

<td>Consenso al<br>
            trattamento dei<br>
            dati personali</td>
            <td><input type="radio" checked name="privacy" value="privacy_SI" class="validate-one-required">SI<p><input
            type="radio" name="privacy" value="privacy_NO">NO</p>
            </td>
        </tr>

Thanks

Hi klikkete,

which Chronoforms version do you have ? this is not possible with V3 at the moment, but possible with V2.5 but will need some code written, many examples on old forum posts!

Regards,

Max