Header Error - Not sure where to put the Header Line

[kenwvs]

I am getting the following error:

Warning: Cannot modify header information - headers already sent by (output started at /home/forsa7/public_html/functions.php:155) in /home/forsa7/public_html/uploadform.php on line 228

I don't understand what is happening here, and am including part of the code, to see if you can tell me what I need to change.

I need the page to go to a confirmation page if there are no errors when the validation has run, but am not really sure where to put the header, so it doesn't cause an error, yet, takes me to the confirmaton page.

  [code]  php:case 'BidIncrement':
                                            $bi = BidIncrement($val,$itemType[$_POST['item_type']]);
                                            if (!$bi[0]) {
                                                    $err[] = $key;
                                                    $err_msg[$key] = $bi[1];
                                            }
                                            break;
                                    case 'ReservePrice':
                                            $rp = ReservePrice($val,$itemType[$_POST['item_type']]);
                                            if (!$rp[0]) {
                                                    $err[] = $key;
                                                    $err_msg[$key] = $rp[1];
                                            }
                                            break;
                                    }
        }
            if (!empty($err)) $valid = false;
            if ($valid) {
            header ("uploadform2.html");
            exit;
          }
            }
    ?>
[/code]


This is also the code from the Submit Button

<form method="POST" action="uploadform.php">

[GingerRobot]

well in the file functions.php on line 155 there is some output to the browser.

Either remove this output, or take a look at the function ob_start();