Grabbing Session variables and header redirects

I was able to get my login page to 'properly' authenticate my users. However, I do have one resulting problem with giving other pages the ability to check for an 'authentication' variable AND then redirect with a "header('Location: http://www.someplaceelse.com/dir1/nextpage.php?avariable=astatus');" I receive the following warning message: Warning: Cannot add header information - headers already sent by (output started at /export/.../here_is_your_info.php:9) in /export/.../here_is_your_info.php on line 13 This is my code in page 1 (the login page)Name: login.php (after truly authenticating the user from information contained within the database)... <?php $redirectLoginSuccess="http://www.mysite.com/here_is_your_info.php"; $redirectLoginFailed="http://www.mysite.com/login.php"; ?> <?php note://user gets the green light IF user gets the green light.... ... session_register("mysecurityvariable"); $login_failed = false; $_SESSION["mysecurityvariable"] =$login_failed; header ("Location: $redirectLoginSuccess"); exit; ....... ...... note://user gets the red light session_register("mysecurityvariable"); $login_failed = true; $_SESSION["mysecurityvariable"] =$login_failed; header ("Location: $redirectLoginFailed"); exit; .... ?> My code reads in page 2 (page needing to test for authentication):Name: here_is_your_info.php <?php note:// redirect to login if invalid user authorization session_start(); note:// causes problems with session_cache_limiter if ((!isset($_SESSION['mysecurityvariable'])) || ($_SESSION['mysecurityvariable'] != false )){ header( 'Location: http://www.mysite.com/login.php' ); } ?> Ultimately, it looks as though it's complaining about having already received a redirection instruction, even though another page initiated it. I have several other pages that will have a need to check for authentication and, initially, I thought I'd try to incorporate this authentication and redirection code into my top nav bar which happens to be INCLUDED on every page. I changed the code to see to if I could generate different results. NOTE: The code for page 2 works perfectly within one other page on the site and the code is IDENTICAL. Any suggestions would be appreciative.