ปัญหาเรื่อง Ajax Auto Fill Textbox อ่ะครับ มันไม่ยอมขึ้นอ่ะครับ

      var HttPRequest = false;

       function doCallAjax(fidsub,fsub,fgid) {
         HttPRequest = false;
          if (window.XMLHttpRequest) { // Mozilla, Safari,...
             HttPRequest = new XMLHttpRequest();
             if (HttPRequest.overrideMimeType) {
              HttPRequest.overrideMimeType('text/html');
            }
          } else if (window.ActiveXObject) { // IE
             try {
                HttPRequest = new ActiveXObject("Msxml2.XMLHTTP");
            } catch (e) {
              try {
                  HttPRequest = new ActiveXObject("Microsoft.XMLHTTP");
               } catch (e) {}
             }
         }
         
         if (!HttPRequest) {
             alert('Cannot create XMLHTTP instance');
             return false;
          }

         var url = 'AjaxGetFill.php';
          var pmeters = "tidsub=" + encodeURI( document.getElementById(fidsub).value);

            HttPRequest.open('POST',url,true);
 
           HttPRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
           HttPRequest.setRequestHeader("Content-length", pmeters.length);
            HttPRequest.setRequestHeader("Connection", "close");
           HttPRequest.send(pmeters);
            
            
           HttPRequest.onreadystatechange = function()
            {

               if(HttPRequest.readyState == 3)  // Loading Request
               {
                   document.getElementById(fsub).innerHTML = "..";
                }

                if(HttPRequest.readyState == 4) // Return Request
                {
                    var mysubject = HttPRequest.responseText;
                  if(mysubject != "")
                    {
                        var myArr = mysubject.split("|");
                        document.getElementById(fsub).value = myArr[0];
                        document.getElementById(fgid).value = myArr[1];
                    }
                }
                 
           }

      }

<?php

	$stridsub = trim($_POST["tidsub"]);

	include ("connect.php");
    mysql_query("set names tis620");
	$sql = "SELECT * FROM $tblsub WHERE idsub = '".$stridsub."'";
	$query = mysql_query($sql) or die ("Error Query [".$sql."]");
	$result = mysql_fetch_array($query);
	if($result)
	{
		echo $result["sub"]."|".$result["gid"];
	}

	mysql_close();
?>