리스트에서 셀렉트선택 여분필드값 수정 문의

====== list.php ===

<select name="wr_1" id="wr_1_<?php echo $i;?>" onchange="wr_1_chk('<?php echo $i;?>','<?php echo $list[$i]['wr_id'];?>',this.value);">
  <option value="가입신청" <? if($list[$i]['wr_1'] == '가입신청') echo " selected "; ?>>가입</option>
  <option value="설치예약" <? if($list[$i]['wr_1'] == '설치예약') echo " selected "; ?>>설예</option>
  <option value="설치완료" <? if($list[$i]['wr_1'] == '설치완료') echo " selected "; ?>>설완</option>
</select>

 

<script type="text/javascript">
var wr_1_chk = function(wr_num,wr_id,field) {
    $.ajax({
        type:"post",
        url:"<?php echo $board_skin_url;?>/list_up.php",
        data:
        {
            bo_table : g5_bo_table,
            wr_num : wr_num,
            wr_id : wr_id,
            wr_1 : field
        },
        dataType:"html",
         success:function(res){
            $("#wr_1_"+wr_num).val(res);
                if(res){
                    alert(res+"으로 입력");
                }else{
                    alert("변경 실패");
                }
                location.reload();
            }
    });
}
</script>

 

====== list_up.php ===

<?php
if (!defined("_GNUBOARD_")) exit; // 개별 페이지 접근 불가

include_once("./_common.php");

$write_table = $g5['write_prefix'].$_POST['bo_table'];
$sql = " update ".$write_table." set wr_1 = '".$_POST['wr_1']."' where wr_id = '".$_POST['wr_id']."' ";
sql_query($sql);
$sql = "select wr_1 from ".$write_table." where wr_id = '".$_POST['wr_id']."' ";
$row = sql_fetch($sql);

if($row['wr_1'])
  echo $row['wr_1'];
else
 echo '';
?>

이렇게 해 보았는데 계속 변경실패로 수정이 안됩니다.
어디가 문제일까요?