function webPortalLogin()
{
  sendungNr = document.getElementById("txtSendungNr").value;
    
  if (sendungNr !="")
  {

    window.open('http://217.243.229.237/tracking.aspx?User=Tracking&ReferenzNr='+sendungNr+'&fremdnr=no' , "","width=1254, height=768")   
  }
}