CI session not working properly

[eluser]manash007[/eluser]
I have this configuration:
$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 7200;
$config['sess_encrypt_cookie'] = FALSE;
$config['sess_use_database'] = FALSE;
$config['sess_table_name'] = 'ci_sessions';
$config['sess_match_ip'] = FALSE;
$config['sess_match_useragent'] = TRUE;

I am getting session value first time. But in next i am not getting session value....
anbody help me