on localhost add to cart is working fine

$config['sess_cookie_name']     = 'ci_session';
$config['sess_expiration']      = 7200;
$config['sess_expire_on_close'] = FALSE;
$config['sess_encrypt_cookie']  = FALSE;
$config['sess_use_database']    = TRUE;
$config['sess_table_name']      = 'ci_sessions';
$config['sess_match_ip']        = FALSE;
$config['sess_match_useragent'] = TRUE;
$config['sess_time_to_update']  = 300;

    session_id varchar(40) DEFAULT '0' NOT NULL,
    ip_address varchar(45) DEFAULT '0' NOT NULL,
    user_agent varchar(120) NOT NULL,
    last_activity int(10) unsigned DEFAULT 0 NOT NULL,
    user_data text NOT NULL,
    PRIMARY KEY (session_id),
    KEY `last_activity_idx` (`last_activity`)

but not on the hosting saver and i think because codeigniter store cart in session then i try to store session in table as suggested by codeigniter documention but then even log in stop working which use session.
note : when i dont store session in table log-in is working fine as i try add to cart log-in stop working

store session in table == nothing work not log_in nor cart
not store seiion table == only log-in work but not cart

just need to do this
$config['sess_match_useragent'] = FALSE;