<?php

  //Global Variables
  $loggedIn = 0;

  //Receive the form variables from the submitted form.
  $username = $_POST['username'];
  $password = $_POST['password'];

  //Check the form boxes were filled in.
  if(empty( $username) || empty($password)){
    header( 'Location: members.php?message=Must Supply Username and Password');
  }

  //More code below to check the pass etc which works ok

?>