var blockForm;
var input_captcha;
function ajaxChaptcha(bericht_captcha) {
  input_captcha = bericht_captcha;
  toDay = new Date();
  datumtijd = toDay.getTime();
  var xmlHttp;
  try {
    xmlHttp = new XMLHttpRequest();
  } catch (e) {
    try {
      xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
    } catch (e) {
      try {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
      } catch (e) {
        alert("Your browser is old and does not have AJAX support!");
        return false;
      }
    }
  }
  xmlHttp.onreadystatechange = function() {
    if(xmlHttp.readyState == 4) {
      if (xmlHttp.responseText != input_captcha) {
        alert("De ingevoerde code komt niet overeen met de afbeelding.\nProbeer opnieuw.");
        return false;
      } else {
        blockForm.submit();
      }
    }
  }
  var xmlParams = "";
  xmlParams = xmlParams + "captcha=" + bericht_captcha + "&";
  xmlParams = xmlParams + "datumtijd=" + datumtijd + "&";      
  xmlHttp.open("GET", "/content/exec_captcha.asp?" + xmlParams, true);
  xmlHttp.send(null);
}