ติดปัญหาใช้ Ajax ติดต่อดาต้าเบส ช่วยด้วยครับ ผมจะนำไปใช้ครับ Phonegap ครับ

 function doCallAjax(id,num_cat,num_do,importer,act) {
		   
		   
		  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 = 'link_newbook.php';
		  var pmeters = "tCat_id=" + num_cat+"&tA_id=" + id+"&tNum_loop=" +num_do+"&tAct=" +act+"&tImporter=" +importer;

			HttPRequest.open('POST',url,true);

			//HttPRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
		//	HttPRequest.setRequestHeader("Content-Type","charset=windows-874"); 
			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_pro'+id).innerHTML = "Now is Loading...";
				  //document.getElementById('txtMessage'+id).value ="เขียนข้อคิดเห็น";
				  }

				 if(HttPRequest.readyState == 4) // Return Request
				  {			  
					  document.getElementById('mySpan_pro'+id).innerHTML = HttPRequest.responseText;
					 	
						//  focus //
					var el = document.getElementById('mydiv'+id);
						el.tabIndex = 32456;
						el.focus();
  
				  }				
			}

	   }