Warning: Header may not contain more than a single header

[hanspeare_1]

Hi there,

i have recieved this notice

Warning: Header may not contain more than a single header, new line detected in C:\xampp\htdocs\a\Student_Edit_Handler.php on line 53

and these are my codes. Kindly help me to fix this.

<?php
    session_start();
    $session_id = $_SESSION['user_id'];
    if($session_id == null){
       header("location:Student_Edit.php");
       die();
    }
    include 'Connect.php';
    $flag = "success";
    function rollbackData(){
        mysql_query(" ROLLBACK ");
        global $flag; 
        $flag = "error";
        if(mysql_error() != null){
            die(mysql_error());
        }
    }
    $student_id = $_POST['student_id'];
    $first_name = $_POST['first_name'];
    $last_name = $_POST['last_name'];
    $gender = $_POST['gender'];
    $date_of_birth = date("Y-m-d",strtotime($_POST['date_of_birth']));
    $contact_no = $_POST['contact_no'];
    $grade = $_POST['grade'];
    $section = $_POST['section'];
    $LRN = $_POST['LRN'];
    $email1 = $_POST['email1'];
    $email2 = $_POST['email2'];
    $address = $_POST['address'];
    $description = $_POST['description'];
    $imagename = "";
    $flag= "";
        mysql_query("SET AUTOCOMMIT = 0 ");
        if(mysql_error() != null){
            die(mysql_error());
        }
    $query = "UPDATE student_information SET first_name='$first_name',last_name='$last_name',";    
    $query .= "gender='$gender',date_of_birth='$date_of_birth',contact_no='$contact_no',grade='$grade',section='$section',";
    $query .= "LRN='$LRN',email1='$email1',email2='$email2',address='$address',description='$description'";     
    $query .= " WHERE student_id='{$_SESSION['user_id']}'";      
    $result = mysql_query($query, $link_id);
    if(mysql_error() != null){
        die(mysql_error());
    }
    if($result)
    { 
        $flag = "success";
    }
    else
    {
         $flag = "error"; 
    }
    header("location:Student_Edit.php?flag=$flag&student_id=student_id=$student_id");
?>

Please advise