ช่วยดูโค๊ดให้หน่อยค่ะมัน error .......Parse error: syntax error, unexpected '"', expecting T_STRING or T_VARIABLE or T_NUM_STRING

<td class="td-20">
<FORM METHOD='post' ACTION='memort.php'>
<input type='text' name='confirm' value='ok' />
<input type='text' name='tran' value='<?= $txnid ?>' />
<INPUT TYPE='submit' name='submit' value='submit'>
</FORM>
<? 
if(isset($_POST["submit"]))
{
$sql = " UPDATE payments SET req_status='complete' WHERE txnid='$txnid' ";
echo $sql;
$dbQuery = mysql_query($sql); 
} 
?>
</td>

<?php
$txnid = $_GET['txnid'];
?>
<form method="post" action="memort.php">
<input type="text" name="confirm" value="ok" />
<input type="text" name="tran" value="<?php echo $txnid; ?>" />
<input type="submit" name="submit" value="submit">
</form>

<?php
if(isset($_POST['submit']))
{
$txnid = $_POST['txnid'];
$sql = "UPDATE payments SET req_status='complete' WHERE txnid='".$txnid."'";
echo $sql;
$dbQuery = mysql_query($sql);
}