How to validate dynamic fields using jquery validation plugin ?

Question

Hello,

I am trying to validate a form using the jquery validation plugin.

It's usually pretty easy but this time I'm using dynamic field.

The new fields are not being checked so I tryed to remove the validator then to recreate it but It's doesnt seem to work.

$j("#add").click(function(){
        $j("#lignes").append($j(".ligne_vide:last").clone());
        var form = $j('#gestion').get(0);
        $j.removeData(form,'validator');
        $j("#gestion").validate({
            submitHandler: function(form){
                $j.post("index.php?page=_ajax",$j("#gestion").serialize());
            }
        });
    });

Any ideas ?