function chkFormular() {
  var error = 0;
  var h = 60;
  var inc = 16;

  if (document.Formular.Name.value == "") {
    error = error + 1;
    h = h + inc;
  }
   if (document.Formular.Strasse.value == "") {
   error = error + 2;
   h = h + inc;
  }
  if (document.Formular.Ort.value == "") {
    error = error + 4;
    h = h + inc;
  }
  if (document.Formular.TelNumber.value == "") {
    error = error + 8;
    h = h + inc;
  }
  if (document.Formular.Emailadress.value == "") {
   error = error + 16;
   h = h + inc;
  }
   if (document.Formular.Subject.value == "") {
   error = error + 32;
   h = h + inc;
  }
  if (document.Formular.Message.value == "") {
    error = error + 64;
    h = h + inc;
  }
  if (error > 0) {
         var caption = 'Fehler im Formular';
         var url = 'fehler.php?f='+error+'&height='+h+'&width=420';
         var imageGroup = '';
         tb_show(caption,url,imageGroup);
         return false;
  }
}