I'm trying to add a drop down menu populated from mysql database. Here is my code:

```
$sql=  "SELECT id, course_period_id from schedule WHERE STUDENT_ID='$_SESSION[student_id]'";
$result=mysql_query($sql);
$options="";
while ($row=mysql_fetch_array($result)) {
    $id=$row["id"];
    $course_period_id=$row["course_period_id"];
    $options.="<OPTION VALUE=\"$course_period_id\">".$course_period_id.'</option>';
}
echo '</TD></TR></TABLE>';
echo '<SELECT>
                <OPTION VALUE=0>Choose
                <?=$options?>
                </SELECT> ';

```

The problem is that it gives me a drop down menu with zero options. So what should I change in my code? 

Thanks