สอบถาม Form Wizard คืออัพโหลดไฟล์พอกด submit แล้วค่าที่แนบไฟล์มา ไม่มีค่าส่งมา ต้องทำยังไงครับ รบกวนด้วยครับ

<form enctype="multipart/form-data" action="save_permit.php" method="get" class="validation-wizard wizard-circle" >
 <!-- Step 1 -->
  <h6>ข้อมูล</h6>
<section>
<div class="row">
<div class="col-md-4">
                                            <div class="form-group">
                                                <label> รหัสอาคาร : <span class="danger">*</span></label>
                                                <input type="text" class="form-control" name="nBuilding_code">
                                            </div>
                                        </div>
                                        <div class="col-md-4">
                                            <div class="form-group">
                                                <label> โซน : <span class="danger">*</span></label>
                                                <select class="custom-select form-control" name="nId_zone">
                                                    <option value="">-----กรุณาเลือก-----</option>
                                                    <option value="India">India</option>
                                                    <option value="USA">USA</option>
                                                    <option value="Dubai">Dubai</option>
                                                </select>
                                            </div>
                                        </div>
                                    </div>
<div class="row">
                                        <div class="col-md-4">
                                            <div class="form-group">
                                                <label> Group : <span class="danger">*</span></label>
                                                <input type="text" class="form-control" name="cGroup">
                                            </div>
                                        </div>
                                        <div class="col-md-4">
                                            <div class="form-group">
                                                <label> รหัสตามกลุ่ม : <span class="danger">*</span></label>
                                                <input type="text" class="form-control" name="nGroup">
                                            </div>
                                        </div>
                                        <div class="col-md-4">
                                            <div class="form-group">
                                                <label> ชื่ออาคาร : <span class="danger">*</span></label>
                                                <select class="custom-select form-control" name="nId_building">
                                                    <option value="">-----กรุณาเลือก-----</option>
                                                    <option value="India">India</option>
                                                    <option value="USA">USA</option>
                                                    <option value="Dubai">Dubai</option>
                                                </select>
                                            </div>
                                        </div>
                                    </div>
                                </section>
<!-- Step 2 -->
                                <h6>แนบไฟล์แบบและคู่มือ</h6>
<section>
                                    <div class="row">
                                        <div class="col-md-6">
                                            <div class="form-group">
                                                <label>แบบงานระบบสถาปัตย์</label>
                                                <div class="fileinput fileinput-new input-group" data-provides="fileinput">
                                                    <div class="form-control" data-trigger="fileinput"> <i class="glyphicon glyphicon-file fileinput-exists"></i> <span class="fileinput-filename"></span></div> <span class="input-group-addon btn btn-default btn-file"> <span class="fileinput-new">Select file</span> <span class="fileinput-exists">Change</span>
                                                    <input type="hidden">
                                                    <input type="file" name="Design_arc"> </span> <a href="#" class="input-group-addon btn btn-default fileinput-exists" data-dismiss="fileinput">Remove</a>
                                                </div>
                                            </div>
                                        </div>
                                        <div class="col-md-6">
                                            <div class="form-group">
                                                <label>คู่มืองานระบบสถาปัตย์</label>
                                                <div class="fileinput fileinput-new input-group" data-provides="fileinput">
                                                    <div class="form-control" data-trigger="fileinput"> <i class="glyphicon glyphicon-file fileinput-exists"></i> <span class="fileinput-filename"></span></div> <span class="input-group-addon btn btn-default btn-file"> <span class="fileinput-new">Select file</span> <span class="fileinput-exists">Change</span>
                                                    <input type="hidden">
                                                    <input type="file" name="Manual_arc"> </span> <a href="#" class="input-group-addon btn btn-default fileinput-exists" data-dismiss="fileinput">Remove</a>
                                                </div>
                                            </div>
                                        </div>
                                    </div>
                                </section>
                            </form>

$file_desi_arc = $_FILES['Design_arc'];
echo $file_desi_arc;

var form = $(".validation-wizard").show();

$(".validation-wizard").steps({
    headerTag: "h6"
    , bodyTag: "section"
    , transitionEffect: "fade"
    , titleTemplate: '<span class="step">#index#</span> #title#'
    , labels: {
        finish: "Submit"
    }
    , onStepChanging: function (event, currentIndex, newIndex) {
        return currentIndex > newIndex || !(3 === newIndex && Number($("#age-2").val()) < 18) && (currentIndex < newIndex && (form.find(".body:eq(" + newIndex + ") label.error").remove(), form.find(".body:eq(" + newIndex + ") .error").removeClass("error")), form.validate().settings.ignore = ":disabled,:hidden", form.valid())
    }
    , onFinishing: function (event, currentIndex) {
        return form.validate().settings.ignore = ":disabled", form.valid()
    }
    , onFinished: function (event, currentIndex) {
        let this_ = $(this);
        let url = this_.attr("action");
        let data = this_.serialize();
        $.post(url,data,function(res){
            if(res == 1){
                swal({
                    title: "บันทึกสำเร็จ",
                    type: "success"
                }
            }
        })
    }
})