output ajax error

//controllel
<?php
class ajax_eceran extends CI_Controller
{

    function __construct() {
        parent::__construct();
        $this->load->admin_model('pos_model');
    }

 	function ambil_data(){
        $modul=$this->input->post('modul');
        //$product_id=$this->input->post('product_id');
        echo $this->input->post('isi');

        /*if($modul=="eceran"){
           //echo $this->Pos_model->get_harga_eceran($groups_id);
            echo $modul;
        }*/
    }

}

//ajax
$(function(){
        $.ajaxSetup({
            type:"POST",
            url: "<?php echo base_url('ajax_eceran/ambil_data') ?>",
            cache: false,
        });

        $("#groups_eceran").change(function(){
            var value=$(this).val();
            if(value>0){
                $.ajax({
                    data:{isi:value},
                    success: function(responde){
                        $("#grup_h").val(responde);
                        //$("#grup_h").attr("placeholder", respond);
                    }
                })
            }
        });
    })

//view
<div class="form-group" id="tampil_meter">
                        <label for="h_eceran" class="col-sm-4 control-label">Pilih Group Harga</label>
                        <div class="col-sm-8">
                            <?php echo group_eceran('groups_eceran', 'sma_price_groups', 'name', 'id', $groups_eceran); //style="display: none"?>
                        </div>
                    </div>

                    <div class="form-group">
                        <label for="grup_h" class="col-sm-4 control-label">Group Harga</label>
                        <div class="col-sm-8">
                            <input type="text" class="form-control" id="grup_h" name="grup_h" placeholder="Group Harga" value="<?php echo $grup_h; ?>">
                        </div>
                    </div>