I got this error while adding a member to my newly created DAG, the Windows was 2012 and Exchange is 2013. it was some how strange because with Exchange 2010 I did not face such error before. after searching I found that I need to manually add the first member of the DAG the full control allow permission on the DAG1 object in Active Directory. then I have to disable the object. when adding the new DAG member the DAG object will be enabled by itself again.
note that you do not have to repeat the same steps while adding addition DAG members