为什么session无效？？郁闷

<?



// page1.php



session_start();



echo 'Welcome to page #1';



$_SESSION['favcolor'] = 'green';

$_SESSION['animal']   = 'cat';



// Works if session cookie was accepted

echo '<br /><a href="session_get.php">page 2</a>';



// Or maybe pass along the session id, if needed

echo '<br /><a href="session_get.php?' . session_id() . '">page 2</a>';



?>

<?

// page2.php



session_start();



echo 'Welcome to page #2<br />';



echo $_SESSION['favcolor']; // green

echo $_SESSION['animal'];   // cat



// You may want to use SID here, like we did in page1.php

echo '<br /><a href="page1.php">page 1</a>';

?>