[jQuery] [validate] Dependent fields - blank selector

[carter]

I have a feedback form where if the user checks the 'Reply required'
checkbox (replyCB) then they must complete either the email field
(emailTF) or the phone field (phoneTF). I've searched through a lot of
posts and tried some different ways of doing this with the validation
plug in but can't get it to work successfully. In fact I'm having
difficulty getting the :blank rule to work at all. My validation
script is below. Any ideas where I'm going wrong?

Thanks in advance.

$().ready(function() {

        // validate signup form on keyup and submit
        $("#addComment").validate({
                rules: {
                        nameTF: "required",
                        commentsTA: "required",
                        emailTF: { /*if the reply box is checked and the phone 
field is
blank ask for an email address*/
                                required: "#replyCB:checked, #phoneTF:blank",
                                email: true
                        },
                        phoneTF: { /*if the reply box is checked and the email 
field is
blank ask for a phone number*/
                                required: "#replyCB:checked, #emailTF:blank"
                        }
                },
                messages: {
                        nameTF: "* Required",
                        commentsTA: " * Required",
                        emailTF: " * Required",
                        phoneTF: " * Required"
                }
        });
});