What version of Management Studios are you installing.

I had a case where third party software installed SQL Server 2008 R2 Express

on a SQL Server 2008 server.

SQL requires you to use the Management Studios for the highest version

of SQL Server. In this case, I needed to add SQL Server 2008 R2 management

studios to be able to be able to work with the maintenance plans for the

SQL Server 2008 instance.