This document explains why you might not see any new Microsoft patches as missing on Server 2008 R2 or Windows 7 machines.
Microsoft patches released after April 2013 are not being detected as missing on 2008 R2 or Windows 7 machines.
This occurs when Service Pack 1 is not applied to Server 2008 R2 and Windows 7 machines.
Apply Service Pack 1.
Re-scan and you should now be seeing patches released after April 2013 as missing.