One of my earlier Exchange 2010 deployments was at a client that had modified the default inheritance settings of Active Directory such that default security permissions did not apply to some Organizational Units (OUs). This prevented ActiveSync from creating necessary objects and setting necessary attributes to provision iPhones for these users against their Exchange 2010 mailboxes. Similar issues occur if you attempt to configure an ActiveSync device for a mailbox associated with a user that is a member of certain privileged groups within Active Directory (e.g. Domain Admins, Enterprise Admins, etc.).

To resolve this issue for the specific case at my client, we simply needed to enable inheritance on the OUs or users where it had previously been disabled.

AD Permissions

Resolving this issue for members of privileged groups is a bit more complicated. Basically, the lack of inheritance is by design for users that are members of privileged AD groups. Every hour, a background process runs on domain controllers to apply the permissions assigned to the AdminSDHolder template object to all members of privileged groups. You can review the permissions that will be applied by launching Active Directory Users and Computers, enabling Advanced Features within the View menu, and then reviewing the security permissions of the AdminSDHolder object within the System OU.

--> Please see the rest on the blog, the true solution is definitely to enable inheritance, it is disabled when you are admin...

http://info.kraftkennedy.com/blog/bid/102097/Exchange-2010-Notes-from-the-Field-ActiveSync-and-Active-Directory-Permissions-Inheritance