如何使用jquery验证插件验证select2元素？

我使用select2 3.5.2和 jquery验证1.13.1.我可以使用验证插件“highlight”方法为select2元素添加错误类,但是当我选择一个值时,我无法删除该错误类.我怎么解决这个问题？

HTML

<form id="test" class="frm">
    <div>
        <input type="text" name="name" />
    </div>
    <div>
        <label for="singleselect"></label>
        <select class="sl" id="singleselect" name="singleselect">
            <option></option>
            <option value="val1">Val-1</option>
            <option value="val2">Val-2</option>
        </select>
    </div>

    <div>
        <label for="multipleselect"></label>
        <select class="sl" id="multipleselect" name="multipleselect" multiple="multiple">
            <option></option>
            <option value="val1">Val-1</option>
            <option value="val2">Val-2</option>
        </select>
    </div>

    <button class="btn">Submit</button>
</form>

JS

$(document).ready(function () {

    $('.sl').select2({
        placeholder:'Select'   
    })

    $.validator.setDefaults({
        ignore: []
    });

    $('#test').validate({
        errorElement: 'span',errorClass: 'error',rules: {
            singleselect:'required',multipleselect:'required',name:'required'
        },highlight: function (element,errorClass,validClass) {

        var elem = $(element);

        elem.addClass(errorClass);

    },unhighlight: function (element,validClass) {
        var elem = $(element);

            if(elem.hasClass('sl')) {
                elem.siblings('.sl').find('.select2-choice').removeClass(errorClass);
            } else {
                elem.removeClass(errorClass);
            }
        }
    });

});

https://jsfiddle.net/8Lyfa3k2/6/

$('select').on('change',function() {  // when the value changes
    $(this).valid(); // trigger validation on this element
});

unhighlight: function (element,validClass) {
    var elem = $(element);
    elem.removeClass(errorClass);
}