Export txt dengan batasan waktu

Halo Master,

Mau tanya dong apa ada yg salah dengan script saya ya? <a href='https://drive.google.com/file/d/1RcpG70OodRzAhkUGLfiaxAlhZQ-bECfM/view'>Export File ScreenShot</a> Ini file index.php nya

<form method="POST" action="export3.php">
 <div class="modal-sm">
   <div class="modal-content">
  <div class="modal-header">
    <h4 class="modal-title">Print Filter ?
    </h4>
  </div>
  <div class="modal-body">
    <div class="control-group">
   <label class="col-sm-2 control-label">Start Date</label>
   <div class="col-sm-6">
   <input type="datetime-local" name="from" id="stayf" class="form-control" style="width:515px;height:25px">
   </div>
     </div>
     <div class="control-group">
   <label class="col-sm-2 control-label">End Date</label>
   <div class="col-sm-8">
   <input type="datetime-local" name="end" id="stayf" class="span5" style="width:515px;height:25px">
   </div>
     </div>
  </div>

  <div class="modal-footer">
    <button data-dismiss="modal" class="btn btn-default" type="button">Cancel
    </button>
    <button class="btn btn-info" type="submit" name="submit" value="export" onclick="return valid();">EXPORT FILE
    </button>
  </div>
   </div>
 </div>
</form>

Ini file export.php

<?php

if(isset($_POST["export"]))  {

// nama file hasil export
$namaFile = "data.txt";

// koneksi ke mysql
$dbname = "logabsensi";
$dbuser = "dewean";
$dbpass = "53cur1ty";
$dbhost = "localhost";

mysql_connect($dbhost, $dbuser, $dbpass);
mysql_select_db($dbname);

// header file text
header("Content-type: text/plain");
header("Content-Disposition: attachment; filename=".$namaFile);

// query sql baca semua data dalam tabel
$query = "SELECT * FROM punchlog where bsevtdt>= '".$_POST["from"]."' AND bsevtdt<= '".$_POST["end"]."'";
$hasil = mysql_query($query);
while ($data = mysql_fetch_array($hasil))
{
    echo "31";
	$date=date_create($data["bevtdt"]);
	echo date_format($date,"Ymd");
	echo date_format($date,"Hi");
	echo "000";
	echo "$data[tk]";
	echo "000";
	echo "$data[user_id]";
	echo "0001\n";
}
          fclose($output);
}

?>