ip address - name using gethostbyaddr

[rupertbj]

Please can someone tell me why this doesn't work!!!

	setcookie( "user", $user, "0" );
	$IP_address = getenv("REMOTE_ADDR");
	$IP_name = gethostbyaddr( $IP_address );
	$user_agent = getenv("HTTP_USER_AGENT");
	$db = "register";
	$link = mysql_connect( "host", "user", "pass" );
	if ( !$link ) die( "Couldn't connect to MySQL" );
	mysql_select_db( $db, $link ) or die( "Couldn't open $db: ".mysql_error() );
	$query = "REPLACE INTO userTable VALUES ( '', '$user', '$password', now(), '$IP_address', '$IP_name', '$user_agent' ) "; 
	mysql_query( $query, $link ); 
	mysql_close( $link );

I checked the manual already.

Thanks.

[phpmaven]

So if run the following:
<?
$IP_address = getenv("REMOTE_ADDR");
$IP_name = gethostbyaddr( $IP_address );
$user_agent = getenv("HTTP_USER_AGENT");
echo "IP_address = $IP_address<BR>";
echo "IP_name = $IP_name<BR>";
echo "user_agent = $user_agent<BR>";
?>
It doesn't echo back what you need?