为什么这里没有输出，也没报错

Question

<?php
 $ms_host="localhost";
 $ms_user="sa";
 $ms_pass="sa";
 $ms_data="his";
 $ms_conn=mssql_connect($ms_host,$ms_user,$ms_pass);
 mssql_select_db('his',$ms_conn);
 $sql ="select top 1 * from zsb_customer";
 $res=mssql_query($sql,$ms_conn);

while ($result=mssql_fetch_array($res)){
  ?>
<ul>
   <li><?php  $result[ctm_name] ?></li>
   <li><?php  $result[ctm_code] ?></li>
</ul>
<?php   
};

$mssql_close($ms_conn);
?>

Answer 1