Eblyn,
I've seen the same thing with W2K8, W2K8R2, and W2K12 servers. I cannot send the DP client agents remotely from the cell manager to a new client - I keep getting 5 Access Denied.
I have to do a manual install on the client, sometimes import (sometimes it does import automatically), and then I can run backups and enable ECC or whatever. It is just on the initial install where I see the issues.
And my cell managers are both W2K3 and W2K8 R2, so it ain't the cell manager OS that is the issue. I think it's some MS security thing they kicked off in newer OSes.
Ken