Session vars troubles

[kr4mer]

Hi folks,
I have a problem here with session vars.
I have 3 pages: page1.php is just a silly login/authentication form (no session there!), in page2.php I collect credentials from page1.php (login password), I check them with a mysql db and I use some user's details to store them into session variables (the idea is to start a session for validated users only).
Everything works fine till here. In page2.php I have a search form and I use the information the user types here, together with the value of session vars to create page3.php.
Unfortunately although in page3.php I can get the right value of the $_POST variables I cannot get the session vars.
If I echo this $_SESSION['FRST_VAR'] I receive an 'Undefined index FRST_VAR' error.
Could some of you tell me why is that?
Thanks

[code]
----------------
#
# page2.php
#
?php>
session_start();

echo '<script language="JavaScript" src="scriptfile.js"></script>';        /*  see down below  */
// some mysql queries here to validate users and get some information about them

$_SESSION['FRST_VAR']=userinfo_1;
$_SESSION['SCND_VAR']=userinfo_2;

// some html stuff here to make the page less boring

echo '<form name="form1" method=POST action="page3.php">';
echo 'Data_1:<input type="text" name="box1" size=30>';
echo 'Data_2: <input type="text" name="box2" size=30>';
echo '<a href="_javascript_:funct_check();">
echo '<img name="submitbutton" src="submit.jpg" border=0>';
echo '</form>';

/* I want to see the value of vars  */
echo $_SESSION['SCND_VAR'];         /*  it actually echoes the right userinfo_2 value */
?>

-------------------
#
# page3.php
#
?php>
session_start();

/* Undefined index  error comes from here */
echo $_SESSION['FRST_VAR'];  
echo $_SESSION['SCND_VAR'];

$info1=$_POST['box1'];        /* these have the right values typed in page2.php */
$info2=$_POST['box2'];        

// stuff...

?>
-------------------
#
# scriptfile.js
#
function func_check()
{
    if (document.form1.box1.length==0 && document.form1.box2.length==0)
        alert('You can't do that!');
    else
        document.form1.submit();
}
[/code]