function clickButton(e, buttonid){
      var evt = e ? e : window.event;
      var bt = document.getElementById(buttonid);
      if (bt){ 
        if (evt.keyCode) code = evt.keyCode;
        else if (evt.which) code = evt.which;
          if (code == 13){ 
                bt.click(); 
                return false; 
          } 
      } 
}