Mailchimp : new registred user not added into

I wanted to set up S2Member with Mailchimp and cannot get it to work together. API, list names and group names have been double checked. When I test member subscriptions the API connects with Mailchimp which is acknowledged by Mailchimp (I get an OK in the API connection list from MailChimp), but no new subscriber is added to the list.
I checked the log and found, that the merge(0) (E-Mail address) does not appear anywhere, so I suspect that it is not forwarded to MailChimp.
Here is the log-file:

LOG ENTRY: Sat Dec 7th, 2013 @ precisely 6:30 pm UTC
PHP v5.3.16 :: WordPress v3.7.1 :: s2Member v131126 :: s2Member Pro v131126
Memory 29.08 MB :: Real Memory 29.25 MB :: Peak Memory 29.11 MB :: Real Peak Memory 29.25 MB
fabrice-ruer.fr/senregistrer/
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:25.0) Gecko/20100101 Firefox/25.0
array (
‘function’ => ‘process_list_servers’,
‘func_get_args’ =>
array (
0 => ‘subscriber’,
1 => ‘0’,
2 => ‘damienr’,
3 => ‘raouldufy’,
4 => ‘dams5@hotmail.com’,
5 => ‘damien’,
6 => ”,
7 => ‘78.219.230.85’,
8 => true,
9 => true,
10 => 8,
),
‘api_method’ => ‘listSubscribe’,
‘list’ => ‘e0074a796a’,
‘list_id’ => ‘e0074a796a’,
‘merge_array’ =>
array (
‘MERGE1’ => ‘damien’,
‘MERGE2’ => ”,
‘OPTIN_IP’ => ‘78.219.230.85’,
‘OPTIN_TIME’ => ‘2013-12-07 18:30:48’,
),
‘api_merge_array’ =>
array (
‘MERGE1’ => ‘damien’,
‘MERGE2’ => ”,
‘OPTIN_IP’ => ‘78.219.230.85’,
‘OPTIN_TIME’ => ‘2013-12-07 18:30:48’,
),
‘api_email_type’ => ‘html’,
‘api_double_optin’ => true,
‘api_update_existing’ => false,
‘api_replace_interests’ => true,
‘api_send_welcome’ => false,
‘api_response’ => true,
‘api_success’ => true,
‘api_properties’ =>
NC_MCAPI::__set_state(array(
‘version’ => ‘1.3’,
‘errorMessage’ => ”,
‘errorCode’ => ”,
‘apiUrl’ =>
array (
‘scheme’ => ‘http’,
‘host’ => ‘api.mailchimp.com’,
‘path’ => ‘/1.3/’,
‘query’ => ‘output=php’,
‘prefix’ => ‘us3’,
),
‘timeout’ => 300,
‘chunkSize’ => 8192,
‘api_key’ => ‘xxxxxxxx/api/key/sec’,
‘secure’ => true,
)),
)

Please Help me
Fabrice