I have an AD setup with a child/root. I ran all the preps from the root DC, and I was able to install my first CAS server in the child domain just fine. When I go to install the second CAS server the install fails and says: Error: Could not find the default Administrative Group 'Exchange Administrative Group (FYDIBOHF23SPDLT)' I know this is the Admin group Exchange 2007 installs for backward compatibility, and this group exists as I can see it in ESM on my Exchange 2003 servers yet. The first CAS server installed fine. Any ideas? Thanks

Strange Run setup /preparead again, that may fix if something is messed up

I found out the issue. The account I was running the install as did not have all the correct Exchange permissions. Hope that helps anyone else seeing this issue.