[jQuery] (validate) Problems with additional methods...

Hello everybody!
I'm trying to use a custom method for validate one of my input's form,
but no way.
Neither the 'additional-methods.js' included in the plugin pack work
for me ....Seems to be ok, but no idea.
This is a resume of my code:
-JAVASCRIPT-
<script type="text/javascript">
$.validator.setDefaults
{
    submitHandler: function
{
        $
"#cForm"
.ajaxSubmit
{
            url:'inc/request.php',
            target: '#form-box',
            success: function
{
                return false;
            },
            resetForm: true
        }
;
    }
}
;
$
document
.ready
function
{
    $
"#cForm"
.validate
{
        rules:{
            nif: "alphanumeric",
        },
        messages: {
            nombre: "campo obligatorio",
            email: {
                required: "campo obligatorio",
                email: "email no valido"
            },
            telefono: {
                required: "campo obligatorio",
                digits: "solo numeros"
            },
            nif: "campo obligatorio",
            legal: "campo obligatorio"
        },
        errorElement: "em",
        errorPlacement: function
error, element
{
            if
element.is
":radio"

                error.appendTo
element.parent
.parent
;
            else if
element.is
":checkbox"

                error.appendTo
element.parent
;
            else
                error.prependTo
element.parent

;
        }
    }
;
}
;
</script>
-HTML-
...
<form action="" method="post" id="cForm">
<div>
<label for="nombre">Nombre y Apellidos</label>
<input class="required" type="text" size="25"
name="nombre" id="nombre" value="" maxlength="100"/>
</div>
<div>
<label for="nif">NIF</label>
<input class="required" type="text" size="9"
name="nif" id="nif" value="" maxlength="9"/>
</div>
<div>
<label for="telefono">Teléfono</label>
<input class="required digits" type="text"
size="10" name="telefono" id="telefono" value="" maxlength="15"/>
</div>
<div>
<label for="email">E-mail</label>
<input class="required email" type="text"
size="25" name="email" id="email" value="" maxlength="100"/>
</div>
<div class="row">
<input class="required" name="legal" id="legal"
type="checkbox"/>
<label for="legal">He leído y acepto las bases
legales</a></label>
<input type="submit" name="submit" id="send"
value="" />
</div>
</form>
...
Thanks in advance!
Best Regards,
Andrea