ช่วยดูให้หน่อยนะครับ เกี่ยวกับเรื่อง ของ radio ที่ส่งค่าโดย javacript

<script language="JavaScript">
	   var HttPRequest = false;

	   function doCallAjax(Mode) {
		  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) {}
			 }
		  } 
		  
		
			
	
		  var url = 'excel_ordersave.php';
		  var pmeters = "tRequest_name=" + encodeURI( document.getElementById("txtRequest_name").value) +
						"&tRequest_date=" + encodeURI( document.getElementById("txtRequest_date").value ) +
						"&tEquipment=" + encodeURI( document.getElementById("Equipment").value ) +
						"&tChemical=" + encodeURI( document.getElementById("Chemical").value ) +
						"&tEbzyme=" + encodeURI( document.getElementById("Ebzyme").value ) +
						"&tOther=" + encodeURI( document.getElementById("txtOther").value ) +
						"&tProject=" + encodeURI( document.getElementById("txtProject").value ) +
						"&tRequested_objective=" + encodeURI( document.getElementById("txtRequested_objective").value ) +
						"&tDescription=" + encodeURI( document.getElementById("txtDescription").value ) +
						"&tSupplier_name=" + encodeURI( document.getElementById("txtSupplier_name").value ) +
						"&tSize=" + encodeURI( document.getElementById("txtSize").value ) +
						"&tQuantity=" + encodeURI( document.getElementById("txtQuantity").value ) +
						"&tPrize=" + encodeURI( document.getElementById("txtPrize").value ) +
						"&tMode=" + Mode;
			  if (!HttPRequest) {
			 alert('Cannot create XMLHTTP instance');
			 return false;
		  }
		    	//เช็คค่า ว่าได้ทำการ เลือก redio หรือป่าว ถ้าไม่ได้เลือกให้แสดงข้อความแสดง
						var Equipment=document.getElementById('Equipment');
						var Chemical=document.getElementById('Chemical');
						var Ebzyme=document.getElementById('Ebzyme');
						
						if (Equipment.checked) {Order_Type = Equipment.value;} 
						else if (Chemical.checked) {
						Order_type = Chemical.value;
						} else if (Ebzyme.checked) {
						Order_type = Ebzyme.value;
						} else {
						alert ("กรุณาเลือก Order Type ! ")
						}
						
						alert (Order_type);
						req.onreadystatechange = function(){
						
						if(req.readyState == 4){
						if(req.status == 200){
						
						}
						}
						
						}			
												
				///*******************************************				
			
			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("mySpan").innerHTML = "Now is Loading...";
				  }

				 if(HttPRequest.readyState == 4) // Return Request
				  {
				   document.getElementById("mySpan").innerHTML = HttPRequest.responseText;
				   document.getElementById("txtRequest_name").value = '';
				   document.getElementById("txtRequest_date").value = '';
				   document.getElementById("Equipment").value = '';
				   document.getElementById("Chemical").value = '';
				   document.getElementById("Ebzyme").value = '';
				   document.getElementById("txtOther").value = '';
				   document.getElementById("txtProject").value = '';
				   document.getElementById("txtRequested_objective").value = '';
				   document.getElementById("txtDescription").value = '';
				   document.getElementById("txtSupplier_name").value = '';
				   document.getElementById("txtSize").value = '';
				   document.getElementById("txtQuantity").value = '';
				   document.getElementById("txtPrize").value = '';
				  
				  }
				
			}
			
		


	   }
	</script>

<td><font color="#006600" size="2"><b>Request Name</b></font><font color="#006600" size="2"><b>(ผู้ขอซื้อ):</b></font></td>
                        <td><input type="text" name="Request_name"  value="<? echo $_POST['Request_Name']; ?>" id="txtRequest_name"/></td>
                        <td><font color="#006600" size="2"><b>Request Date:</b></font> </td>
                        <td><input type="text" name="Request_date"  value="<? echo $_POST['Request_date']; ?>" id="txtRequest_date"/></td>
                      </tr>
                      <tr>
                        <td><font color="#006600" size="2"><b>Order Type:</b></font></td>
                      </tr>
                      <tr>
                        <td><input type="radio" value="Equipment" name="Order_type" id="Equipment" />
                            <font color="#006600" size="2">Equipment (วัสดุอุปกรณ์)</font></td>
                        <td><input type="radio" value="Chemical" name="Order_type" id="Chemical" />
                            <font color="#006600" size="2">Chemical (สารเคมี)</font></td>
                        <td><input type="radio" value="Ebzyme" name="Order_type" id="Ebzyme" />
                            <font color="#006600" size="2">Enzyme (เอนไซม์)</font></td>
                        <td>
                            <font color="#006600" size="2"><input type="radio" name="Order_type" id="Other" onClick="ck_frm();" />Other (อื่นๆ)</font>
                      </td>
                      <td><div id="frm_txt" style="display:none;">
                            <input type="text" name="Other" size="30" id="txtOther"/>
                            </div></td>
                      
                      
                      </tr>