Question about the validation plug-in

Question about the validation plug-in

Hallo,

I start using validation plugin and have a question. I would like to make the list of checkboxes (please see below).
  1. []
  2. []
  3. []
  4. []
  5. []
  6. []
  7. []
The person that decides to check, for instance 4, has to check before all previous checkboxes. It means that someone choosing to check 7 must have checked previously all the checkboxes from 1 to 6. I have tried something similar that I have put below, but it doesn't work (please see the part in green). I would be grateful for any advice.

Thanks in advance

Paul

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
 "http://www.w3.org/TR/html4/loose.dtd">

<html>
<head>
<title>Etapy certyfikacji</title>


<script src="jquery-1.9.1.min.js"></script>
<script src="scripts/dist/jquery.validate.js"></script>

<script>
$.validator.setDefaults({
    submitHandler: function() { alert("submitted!"); }
});

$().ready(function() {

    // validate signup form on keyup and submit
    $("#choice").validate({
        rules: {
            cv: "required",
            competence_test: "required",
            references: {
            required: "#cv:checked",
            required: "#competence_test:checked",
            required: "#philosophy_statement:checked",
            required: "#presentation:checked"
            },





       

        },
        messages: {
            cv: "You must choose at least to send CV and take a competence test",
            competence_test: "You must choose at least to send CV and take a competence test",
            references: {
                required: "You must choose firstly to do previous steps ",
                required: "You must choose firstly to do previous steps ",
                required: "You must choose firstly to do previous steps "
            },
        }
    });

   

});
</script>


</head>
<body>
Wybierz poszczególne etapy procesu certyfikacji, do których chcesz przystąpić.<br />

Pamiętaj, że wybór każdego z kolejnych etapów wymaga uprzedniego wyboru i
zaznaczenia poprzedzających go elementów.
<form id="choice" action="" method="post">
<div>
<label for="cv"><input type="checkbox" name="cv" value="tak" />Curriculum Vitae</label><br />

<label for="competence_test"><input type="checkbox" name="competence_test" value="tak" />Competence test</label><br />

<label for="philosophy_statement"><input type="checkbox" name="philosophy_statement" value="tak" />Philosophy statement</label><br />

<label for="references"><input type="checkbox" name="references" value="tak" />References</label><br />

<label for="knowledge_test"><input type="checkbox" name="knowledge_test" value="tak" />Knowledge test</label><br />

<label for="case_study"><input type="checkbox" name="case_study" value="tak" />Case study</label><br />

<label for="presentation"><input type="checkbox" name="presentation" value="tak" />Presentation</label>

<input class="submit" type="submit" value="Submit"/>

</form>

</body>
</html>