Mailchimp not adding new subcribers or synching existing

Hello,

I have MailChimp installed, and set to not automatically opt-in. The API test is passed.

Adding new users through the front end or admin does not add the user to my mailing list.

Using the Synch feature also does not add any users to my mailing list.

There are no errors in my php log, and my apache log shows this:

09 - - [07/Jan/2012:00:13:14 -0500] "GET /wp-content/themes/bp-social-child/_inc/css/adminbar.css?ver=20110723 HTTP/1.1" 304 - "http://www.blogsforexpats.com/wp-admin/options-general.php?page=mailchimp&updated=true&updatedmsg=0+users+added%2C+0+updated%2C+and+0+spam+users+removed+from+your+list." "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:9.0.1) Gecko/20100101 Firefox/9.0.1"
223.25.13.

In case it matters, I do have the membership plug-in installed. The plug-in is activated, but protection is not yet enabled.

Any ideas where to troubleshoot further?