redirect not working

hi,

my data assist page is not redirecting:

code is:

<?php
// WA Application Builder Insert
if (isset($_POST["OK"])) // Trigger
{
$WA_connection = $cbank;
$WA_table = "parts";
$WA_sessionName = "parts_PartID";
$WA_redirectURL = "parts_Results.php";
if (function_exists("rel2abs")) $WA_redirectURL = $WA_redirectURL?rel2abs($WA_redirectURL,dirname(__FILE__)):"";
$WA_keepQueryString = false;
$WA_indexField = "PartID";
$WA_fieldNamesStr = "PartName|SupplierID|PartSerialNumber";
$WA_fieldValuesStr = "".((isset($_POST["PartName"]))?$_POST["PartName"]:"") ."" . "|" . "".((isset($_POST["Supplier"]))?$_POST["Supplier"]:"") ."" . "|" . "".((isset($_POST["PartSerialNumber"]))?$_POST["PartSerialNumber"]:"") ."";
$WA_columnTypesStr = "',none,''|none,none,NULL|',none,''";
$WA_fieldNames = explode("|", $WA_fieldNamesStr);
$WA_fieldValues = explode("|", $WA_fieldValuesStr);
$WA_columns = explode("|", $WA_columnTypesStr);
$WA_connectionDB = $database_cbank;
mysql_select_db($WA_connectionDB, $WA_connection);
if (!session_id()) session_start();
$insertParamsObj = WA_AB_generateInsertParams($WA_fieldNames, $WA_columns, $WA_fieldValues, -1);
$WA_Sql = "INSERT INTO `" . $WA_table . "` (" . $insertParamsObj->WA_tableValues . ") VALUES (" . $insertParamsObj->WA_dbValues . ")";
$MM_editCmd = mysql_query($WA_Sql, $WA_connection) or die(mysql_error());
$_SESSION[$WA_sessionName] = mysql_insert_id();
if ($WA_redirectURL != "") {
if ($WA_keepQueryString && $WA_redirectURL != "" && isset($_SERVER["QUERY_STRING"]) && $_SERVER["QUERY_STRING"] !== "" && sizeof($_POST) > 0) {
$WA_redirectURL .= ((strpos($WA_redirectURL, '?') === false)?"?":"&").$_SERVER["QUERY_STRING"];
}
header("Location: ".$WA_redirectURL);
}
}
?>

this happens on a blank white page or any page for that fact.

is there something wrong with the code it is producing?

the form action is set to POST.

many thanks