Question : Exchange 2010 setup.com /preparead fails

I am in the process of setting up Exchange 2010 within the existing 2003 organization. I have 2008 and 2003 DC's with domain functional level of 2003. On 2008 DC, so far I have run Setup.com /PrepareLegacyExchangePermissions, Setup.com /PrepareSchema and Setup.com /PrepareAD successfully. When I run Setup.com /PrepareDomain, I get this error message:

    Organization Preparation         ......................... FAILED
     The following error was generated when "$error.Clear(); $arbMbxname = "Syst
emMailbox{1f05a927-" + [System.Guid]::NewGuid().ToString().Substring(9) + "}"; $
arbMbxLastName = "MSExchApproval 1f05a927-3be2-4fb9-aa03-b59fe3b56f4c"; $arbUser
 = @(Get-User -Filter {LastName -eq $arbMbxLastName} -IgnoreDefaultScope -Result
Size 1); if ($arbUser.Length -eq 0) { $arbUser = @(Get-User -Arbitration -Filter
 {LastName -eq $arbMbxLastName} -IgnoreDefaultScope -ResultSize 1); } if ($arbUs
er.Length -eq 0) { Install-UserAccount -Name $arbMbxname -LastName $arbMbxLastNa
me; }" was run: "An error occuried while granting full access permission to the
Organization Management role group on the mailbox "my.domain.com/Users/Syste
mMailbox{1f05a927-7768-47fa-b195-38d70a7f568b}". Error details: Group "29a962c2-
91d6-4ab7-9e06-8728f8f842ea" wasn't found. Please make sure you have typed the n
ame correctly.".

I am not sure what group it is referring to that it doesn't exist and how to remedy this problem.

Answer : Exchange 2010 setup.com /preparead fails

Ok. It worked this time. I think the problem was that I moved Schema Master role from one DC to another and tried running the tool right away without waiting for the replication to happen.