总是显示search failed

function module_datail(){
   var row_num=parseInt(window.event.srcElement.id); 
   var table=document.getElementById('projectstatus');
   var m_date=table.rows[3+row_num].cells[0].innerHTML;
   var p_name=table.rows[3+row_num].cells[2].innerHTML;
   var p_owner=table.rows[3+row_num].cells[3].innerHTML;
   var m_name=table.rows[3+row_num].cells[4].innerHTML;
   var m_owner=table.rows[3+row_num].cells[5].innerHTML;
   if(m_name=='-'&&m_owner=='-')
       alert("对不起，无法查看模块详细信息，请选择具体日期进行查看");
   else{
       Create_xmlhttp();
       var url="php//case_detail?m_date="+m_date+"&p_name="+p_name+"&p_owner="+p_owner+"&m_name="+m_name+"&m_owner="+m_owner;
       xmlHttp.onreadystatechange=function(){
        if(xmlHttp.readyState==4&&xmlHttp.status==200)
        {
            alert(xmlHttp.responseText);
        }
        }
        xmlHttp.open("GET",url,false);
    xmlHttp.send();
  }
   
}

<?php
   header('Content-Type:text/html;charset=GBK'); 
   $m_date=$_GET["m_date"];
   $p_name=$_GET["p_name"];
   $p_name=iconv("UTF-8","GB2312",$p_name);
   $p_owner=$_GET["p_owner"];
   $p_owner=iconv("UTF-8","GB2312",$p_owner);
   $m_name=$_GET["m_name"];
   $m_name=iconv("UTF-8","GB2312",$m_name);
   $m_owner=$_GET["m_owner"];
   $m_owner=iconv("UTF-8","GB2312",$m_owner);
   
   $mysql_server_name="127.0.0.1";
     $mysql_username="root";
     $mysql_password="";
     $mysql_database='summary';
     
     $con=mysql_connect($mysql_server_name,$mysql_username,$mysql_password) or die("connect failed");
     //mysql_query("set names GBK;");
     $sql="select * from AutoModule";
     echo $sql;
     $result=mysql_query($sql) or die("search failed");
     while($row=mysql_fetch_array($result)){
       echo $row[0]." ";
   }
   mysql_free_result($result);
   mysql_close($con);
?>