Authentication Not working

[bump909]

Can anybody tell me why my Authentication.php script does not work on my local machine but works fine on my server. Is there a setting in the php.ini file that needs to be set?
I use PHP ver 4.3.4 with Apache
Here is my code:

<?php

$authorized = FALSE;

// Check for authentication submission.
if ( (isset($SERVER['PHP_AUTH_USER']) AND isset($SERVER['PHP_AUTH_PW'])) ) {

if ( ($_SERVER['PHP_AUTH_USER'] == 'name') AND ($_SERVER['PHP_AUTH_PW'] == 'password') ) { // If the correct values were entered...
	$authorized = TRUE;
}	

}

// If they haven't been authorized, create the pop-up window.
if (!$authorized) {
header('WWW-Authenticate: Basic realm="Administration Login"');
header('HTTP/1.0 401 Unauthorized'); // For cancellations.
}
?>

[tsinka]

Add ini_set("error_reporting",E_ALL); on top of the script.

You might get an (expected) error about "headers already sent"

Add print_r($SERVER); if you don't get any error messages to see if something might be wrong with the $SERVER array.

Thomas

[bump909]

No Problems with headers allready sent as E_ALL is set by default in my config file. Also it works fine on my server.
What should I look for in $_SERVER?