Log In User behaviour issue

So I created a couple of pages for some sort of web admin part of a website so other persons can also add content. I created a table in PMA where DW CS3 gets the username and password. When creating the log in form, after trying to log in, it just keeps coming the same page. After the 'index.php' page, the user should be redirectered to the 'overview.php' page but no luck and beats me really why DW won't make this happen. Please see below for my code.

<?php require_once('../Connections/dbconnect.php'); ?>
<?php
if (!function_exists("GetSQLValueString")) {
function GetSQLValueString($theValue, $theType, $theDefinedValue = "", $theNotDefinedValue = "") 
{
  $theValue = get_magic_quotes_gpc() ? stripslashes($theValue) : $theValue;

  $theValue = function_exists("mysql_real_escape_string") ? mysql_real_escape_string($theValue) : mysql_escape_string($theValue);

  switch ($theType) {
    case "text":
      $theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
      break;    
    case "long":
    case "int":
      $theValue = ($theValue != "") ? intval($theValue) : "NULL";
      break;
    case "double":
      $theValue = ($theValue != "") ? "'" . doubleval($theValue) . "'" : "NULL";
      break;
    case "date":
      $theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
      break;
    case "defined":
      $theValue = ($theValue != "") ? $theDefinedValue : $theNotDefinedValue;
      break;
  }
  return $theValue;
}
}
?>
<?php
// *** Validate request to login to this site.
if (!isset($_SESSION)) {
  session_start();
}

$loginFormAction = $_SERVER['PHP_SELF'];
if (isset($_GET['accesscheck'])) {
  $_SESSION['PrevUrl'] = $_GET['accesscheck'];
}

if (isset($_POST['user'])) {
  $loginUsername=$_POST['user'];
  $password=$_POST['pass'];
  $MM_fldUserAuthorization = "";
  $MM_redirectLoginSuccess = "overview.php";
  $MM_redirectLoginFailed = "index.php";
  $MM_redirecttoReferrer = false;
  mysql_select_db($database_dbconnect, $dbconnect);
  
  $LoginRS__query=sprintf("SELECT `user`, pass FROM admins WHERE `user`=%s AND pass=%s",
    GetSQLValueString($loginUsername, "-1"), GetSQLValueString($password, "text")); 
   
  $LoginRS = mysql_query($LoginRS__query, $dbconnect) or die(mysql_error());
  $loginFoundUser = mysql_num_rows($LoginRS);
  if ($loginFoundUser) {
     $loginStrGroup = "";
    
    //declare two session variables and assign them
    $_SESSION['MM_Username'] = $loginUsername;
    $_SESSION['MM_UserGroup'] = $loginStrGroup;           

    if (isset($_SESSION['PrevUrl']) && false) {
      $MM_redirectLoginSuccess = $_SESSION['PrevUrl'];     
    }
    header("Location: " . $MM_redirectLoginSuccess );
  }
  else {
    header("Location: ". $MM_redirectLoginFailed );
  }
}
?>

All the other pages have the restricted access page behaviour, maybe something to do with that? Thanks for your time.

J.