Upgrading Exchange 2010 to SP2 from SP1

Hi every one ,

I am upgrading my Exchange 2010 enviroment to SP2 from SP1.

I have 2 CAS and 3 MB servers .

I have successfully upgraded 2 CAS and 1 MB server but got stuck at 2nd mailbox. It is showing following error when it  come to update Mailbox role.

This server role can't be installed because the following roles aren't current: AdminToolsRole

I have made registry changes as per following post but unable to find any luck.

http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/07c7c824-13e8-4555-b871-28dd73af4074

Please help.

SSA