Got it. Could you please update to the latest version?
From the v110815 changelog:
(s2Member) Bug fix / Capabilities. When/if you require Custom Capabilities in order to view certain content sections on your site, s2Member was behaving properly in all cases, except for one specific scenario. When an Administrator of the site ( on a normal single-site installation of WordPress ), was attempting to test-view content protected with Custom Capabilities ( this scenario was causing a problem ). What was happening, is that s2Member was seeing that an Adminstrator did not have certain Custom Capabilities defined explicity in their account, and access was being denied ( that's actually, NOT right ). This was in conflict with the way that s2Member handles all other content protection routines with respect to Administrators. Administrators should automatically have access to all protected content, even if Custom Capabilities are not explicity defined in their account. After all, they are Administrators. In short, this release makes it possible for Administrators of a single-site WordPress installation, to have full access to all content; even when/if Custom Capabilities are required. This should help to prevent confusion for site owners just beginning to understand s2Member's functionality with respect to Custom Capabilities.