Session configuration problems

[eluser]LuckyFella73[/eluser]
I have a Flash game that gets all needed values from
my CI application (each click at a Flash button causes
an interaction with my CI php files).

After log-in there a 2 restrictions:

1. after doing nothing (a klick in the Flash game "pings"
a php file) for 30 minutes the session has to be expired

2. after 12 hours playing the session has to
be expired

I tried setting

Code:

$config['sess_expiration'] = 1800;
$config['sess_time_to_update']     = 43200;

When starting the Flash game the session id is send to the
flash game. after each klick the responding php file sends
the actual session id wich is compared with the one that
was set when starting the game. If the session id is not
the same anymore (after expiring) the Flash game gives a message.

Unfortunately I get this message too early.

Any help would be great!

btw: I use CI DB sessions and autoload Sessions, my cookie name has
no underscore and I did set the cookie domain.