Mail chimp integration get subscribers list problem


I am using the mailchimp integration plugin. I am able to add users to mailchimp list that i have created using the function mailchimp_add_user( $uid );

The added user shows up in the mailchimp list as well.

However when i try to retrieve users using these lines

$mailchimp_mailing_list = get_site_option('mailchimp_mailing_list');
$api = mailchimp_load_API();
$unsubscribed_list = mailchimp_get_unsubscribed_users( $api, $mailchimp_mailing_list );

i get an empty array. Can you let me know what could be wrong?

I have tested and both these variables have values $api and $mailchimp_mailing_list