ajax other parameter is null?

Question

why my other paramter is null. "date" and "ids" is null while my "postedFile" and "amount" has a data. but when i try to removed "postedFile" parameter. the ids and date has a value. and it works fine. but i need the postedfile parameter

 

my script

var ids = [];
function add(id, isChecked) {
    if (isChecked) {
        ids.push(id);
    }
    else {
        var i = ids.indexOf(id);
        ids.splice(i, 1);
    }
}

function saveSelected() {
    //var shipmentId = $('#c-shipment-id').val();
    var date = $('#Date').val();
    var amount = $('#Amount').val();
    //var ImageFile = $('#imageUploadForm').val();

    $('#imageUploadForm').on("change", function () {
        var formdata = new FormData($('form').get(0));
        CallService(formdata);
    });

    function CallService(postedFile) {
        $.ajax({
            url: '@Url.Action("index", "payment")',
            type: 'POST',
            data: { ids: ids, amount: amount, date: date, postedFile: postedFile },
            cache: false,
            processData: false,
            contentType: false,
            traditional: false,
            dataType:"json",
            success: function (data) {
                alert("Success");
            }
        });
    }
}

My controller

public ActionResult Index(int?[] ids, decimal? amount, DateTime? date, HttpPostedFileBase postedFile)
{
    return View();
}