Php 无法保存附加表单字段中的值

你好。我试图从附加的文本字段中保存，但无法获取值

这是我的JS

$("#kelasnya").change(function(){
    var kelasid = $("#kelasnya").val();
    var tanggal = $("#datetimepicker_mask_custom").val();
        $.ajax({
            url: '<?=base_url();?>absensi/generateMurid',
            type: 'POST',
            data: {kelas:kelasid,tanggal:tanggal},
            success: function(data, textStatus, jqXHR){
                  var newdata = JSON.parse(data);
                console.log(newdata);
                    $.each(newdata, function(key, val) {
                        $("#isi").append('<tr><td>['+ val.NIK +'] - '+val.NamaSiswa+' </td>'+
                                         '<td><select class="inputan" name="kehadiran[]"><option value="Hadir">Hadir</option>'+
                                         '<option value="Sakit">Sakit</option>'+
                                         '<option value="Izin">Izin</option></select></td>'+
                                         '<td><input name="keterangan[]" type="text" class="inputan form-control"></td></tr>'
                        );
                    });
            }
        });
    });

我只得到这个结果

这是截图

首次加载

在我从Pilih Kelas中选择之后

那么，我怎样才能得到这个值呢

对不起，我的英语不好

 <?php
                $attributes = array('class' => 'form-horizontal', 'id' => '');
                echo form_open_multipart($controller.'/save',$attributes);
                ?>
                    <div class="form-group">
                            <label class="col-sm-3 control-label">Pilih Kelas</label>
                            <div class="col-sm-5">
                            <select id="kelasnya" class="form-control inputan select2" name="kelas">
                            <option value="">---</option>
                            <?php foreach($kelas as $kelasnya) {?>
                                <option value="<?=$kelasnya->ID;?>"><?=$kelasnya->Kelas;?></option>
                            <?php } ?>
                            </select>
                            </div>
                    </div>

                    <div class="form-group">
                            <label class="col-sm-3 control-label">Tanggal Absensi</label>
                            <div class="col-sm-5">
                             <input type="text" value="<?=$defaultdate->skrg;?>" readonly="readonly" name="TanggalLahir" class="form-control" id="datetimepicker_mask_custom" size="12"/>

                            </div>
                    </div>

                 </div>
                  <div class="box-body">
                   <div class = "pre-scrollable">
                    <table id="" class="table table-bordered">
                        <thead>
                            <tr>
                                <td>Nama</td>
                                <td>Absensi</td>
                                <td>Keterangan</td>
                            </tr>
                        </thead>    
                        <tbody id="isi">

                        </tbody>
                    </table>
                    </div>
                        <button class="btn btn-submit" type="submit">Simpan</button>
                  </form>

function save(){

        echo "<pre>";print_r(populateform());
        //echo count($this->input->post('keterangan[]'));
    }

Array
(
    [kelas] => 1
    [TanggalLahir] => 18-12-2016
)