สอบถามเรื่อง ajax ครับผม คือในหนึ่งหน้าผมจะมีการใช้ ajax หลายตัวนครับ ตัวแรกใช้ได้ พอมาตัวที่สองมันใช้ไม่ได้อ่ะครับผม

<script type="text/javascript">
function searchname(Type,Name){
	//Ajax searchname
		  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 = 'include_admin/Searname-ajax.php';
		  var pmeters = "Type=" + Type+
						"&Name=" + Name;
			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("showname").innerHTML = "Now is Loading...";
				  }

				 if(HttPRequest.readyState == 4) // Return Request
				  {			  
					  document.getElementById('showname').innerHTML = HttPRequest.responseText;
				  }				
			}
}
</script>
<script type="text/javascript">
function addproductsale(ProductID,Qty,Price,Point){
	//Ajax sale
		  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 = 'include_admin/add_product-sale.php';
		  var pmeters = "tProductID=" + ProductID+
						"&tQty=" + Qty + "&tPrice=" + Price + "&tPoints=" + Point;
			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("addproduct").innerHTML = "Now is Loading...";
				  }

				 if(HttPRequest.readyState == 4) // Return Request
				  {			  
					  document.getElementById('addproduct').innerHTML = HttPRequest.responseText;
				  }				
			}
}
</script>

<form action="" method="post" id="formsearchname">
<table border="0" align="center">
  <tr>
    <td>ค้นหาลูกค้า</td>
    <td><input name="txtsearch" type="text" id="txtsearch" width="100" value="<?php if(isset($_REQUEST['txtsearch'])){echo $_REQUEST['txtsearch'];}?>"/></td>
    <td><select id="searchcus" name="typename">
    <option value="fname" <?php if ($typename=="fname"){echo "selected=\"selected\"";}?>>ชื่อ</option>
	<option value="nname" <?php if ($typename=="nname"){echo "selected=\"selected\"";}?>>ชื่อเล่น</option>
    </select></td>
    <td><input type="button" value="ค้นหา" name="searchname" id="searchname" onclick="JavaScript:searchname(document.getElementById('txtsearch').value,document.getElementById('searchcus').value);" /></td>
  </tr>
</table>
</form>
<hr />
<span id="showname">
   
</span>
<span id="selectproduct">

          <table border="0" align="center">
          <form action="" id="formproduct" method="post">
            <tr>
              <td>เลือกสินค้า</td>
              <td colspan="4">
             
              <select name="product" id="product">
              <option value="0">กรุณาเลือกสินค้า</option>
			  		<?php 
					$selpro = "select * from product" ;
					$resultsel = mysql_query($selpro);
					while($sepro=mysql_fetch_array($resultsel)){
						$proidshow = $sepro['pro_id'];
						$proname = $sepro['pro_name'];
						if($proid == $proidshow)
						{$sel = "selected";}
						else
						{$sel = "";}
						echo "<option value= '$proidshow' $sel>$proname</option>";
					}
					?>
              </select>
              <input type="hidden" id="productid"  /> 
               </td>
              <td><input type="submit" name="submitpro" id="submitpro" value="เลือก" /></td></form>
            </tr>
            <tr>
              <td>ราคา/หน่วย</td>
              <td><input type="text" name="productprice" id="productprice" value=" <?php echo $propriceshow; ?>" /></td>
              <td>บาท</td>
              <td>คะแนน(VP)</td>
              <td><input type="text" name="productpoint" id="productpoint" value=" <?php echo $propointshow; ?>" /></td>
              <td>คะแนน</td>
            </tr>
            <tr>
              <td>จำนวน</td>
              <td><input type="text" name="productqty" id="productqty" onKeyPress="if (event.keyCode < 48 || event.keyCode > 57 ){event.returnValue = false;}" /></td>
              <td>ชิ้น</td>
              <td></td>
              <td><input type="button" name="submitpro" id="submitpro" value="เพิ่ม" onClick="addproductsale('<?php echo $proid;?>', document.getElementById('productqty').value,document.getElementById('productprice').value,document.getElementById('productpoint').value);" /></td>
              <td>&nbsp;</td>
            </tr>
          </table>
       <hr />
   		</span>
        <span id=addproduct>
		
        </span>