xmlhttp.open()后怎么没有返回任何状态？？？？？？？？？？？

Question

 这句话xmlhttp.open("get", "WebForm3.aspx?ID="+name, false); 
 最后一个参数为true的话就很好，为false的时候没有弹出一个alert().求解!! var sData = dialogArguments; 
   var father_Row= sData.getNewData('cur');
    if(father_Row!=null)    {    
    var name=  document.getElementById("name");  
    name.value= father_Row.cells(1).innerText;
          var xmlhttp;     
       try {              
            xmlhttp = new XMLHttpRequest();         
            } catch (e) {    
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");       
      }               
xmlhttp.open("get", "WebForm3.aspx?ID="+name, false);            xmlhttp.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');    
        //xmlhttp.setRequestHeader("If-Modified-Since","0");
            xmlhttp.send(""); 
       xmlhttp.onreadystatechange = function() {          
      if (4 == xmlhttp.readyState) {            
           if (200 == xmlhttp.status) {
              var Bodys=xmlhttp.responseText;                                       
              alert("获得内容："+Bodys);             
              var div1=  document.getElementById("div1");        
        }                
   else { 
         alert(xmlhttp.status);  
        }      
 }              
 else{ 
       alert(xmlhttp.readyState);
     }
}  
  }