Session wierdness

[liquorvicar]

ok, so at the top of one of my scripts i have:

echo(session_id().'<br>');
print_r($_SESSION);
session_write_close();
die();

which outputs:
1d06ce496058b6cd44544a6440fb0312
Array ( [basket] => wg287234766
[month] => 12
[page] => 1
[region] => 3
[artist] =>
[venue] =>
[display] => default )

but when i open a shell on the box and look at the contents of my session on the server i get:
cat sess_1d06ce496058b6cd44544a6440fb0312
basket|s:11:"wg287234766";
month|i:12;
page|i:1;
region|s:0:"";
artist|s:0:"";
venue|s:0:"";
display|s:7:"default";

now why on earth would all the session data be there EXCEPT the region value?
it's driving me nuts.

[liquorvicar]

bump

[mrhappiness]

on the next page: can you use $_SESSION['region']?

[liquorvicar]

no, that's what awakened me to my problem. it's a search function and it stores the search variables in $_SESSION to cope with the pagination.
what's really weird is that the production server running this website has been working fine for months. the only diff in the server configs as far as i can see with regard to sessions is the value of session.gc_maxlifetime.