Ajax function is not working
===

I need to display name in textbox named txtName with a ajax function. But it not displayed the name in that textbok. The following is my ajax function

    function showName(str)
    {
    if (str.length==0)
      {
      document.getElementById("txtName").innerHTML="";
      return;
      }
    if (window.XMLHttpRequest)
      {// code for IE7+, Firefox, Chrome, Opera, Safari
      xmlhttp=new XMLHttpRequest();
      }
    else
      {// code for IE6, IE5
      xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
      }
    xmlhttp.onreadystatechange=function()
      {
      if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {
        document.getElementById("txtName").innerHTML=xmlhttp.responseText;
        }
      }
    xmlhttp.open("GET","getname.php?q="+str,true);
    xmlhttp.send();
    }