When I try and add a list from the Module interface (/admin/config/services/mailchimp/lists/add) I get a 500 error. Looking at the logs the issue is
PHP Fatal error: Class 'MCAPI' not found in /var/www/somesite.com/sites/all/modules/mailchimp/includes/mailchimp.inc on line 3, referer: http://somesite.com/admin/config/services/mailchimp/lists
I have the library in the correct location and the status report indicates that "The MailChimp MCAPI wrapper library is installed correctly." I am using the 1.3 version of the library.