ajax로 스크랩을 이용해서 저장 버튼을만드는데 validation 에러가 나옵니다

if (!$is_member)
    alert_only("로그인 후 이용하실 수 있습니다.");

// 게시판이 존재하는지
if(!$board[bo_table]) {
    alert('게시판이 존재하지 않습니다.');
}

$sql = " select count(*) as cnt from {$g5['scrap3_table']} where mb_id = '{$member['mb_id']}' and bo_table = '$bo_table' ";
$row = sql_fetch($sql);

if ($row['cnt']) {
    alert_close('이미 등록하신 게시판입니다.');
}

sql_query("insert into {$g5['scrap3_table']} set mb_id = '{$member['mb_id']}', bo_table = '{$bo_table}' ");

alert_close(" '{$board['bo_subject']}'를 등록하였습니다.");

<script type="text/javascript">

function scrap_submit()  {
    var form = $("form[name=favoriteInfo]").serialize();

        $.ajax({

        type: 'POST',

        url: g5_bbs_url+"/scrap3_add.php",

        data: form,

      success: function(data) {
          alert("성공");         
      }, 

      error: function() {
           alert("실패");
      }        
        });
     }); 

</script>

<form name="favoriteInfo" action="<?php echo G5_BBS_URL?>/scrap3_add.php" method="post"> >
    <input type="hidden" name="bo_table" value="<?php echo $bo_table ?>">
    <input type="hidden" name="mb_id" value="<?php echo $mb_id ?>">
</form>

<?php if ($scrap3_href) { ?><a href="javascript:;" onclick="scrap_submit()" class="btn btn-black">추가하기</a><?php } ?>

<script type="text/javascript">

function scrap_submit()  {
    var form = $("form[name=favoriteInfo]").serialize();

        $.ajax({

        type: 'POST',

        url: g5_bbs_url+"/scrap2_add.php",

        data: form,

      success: function(data) {
          alert("성공");         
      }, 

      error: function() {
           alert("실패");
      }        
        });
     }); 

</script>