Exchange SP1 Edge Transport Install Error

Hi everyone,

I've successfully installed multiple Mailbox and CAS 2013 SP1 servers into an existing Exchange 2010 environment.

However, when I get to the Edge Transport role on a separate server, at step 7 of 9, it throws the following error:

Error:

The following error was generated when "$error.Clear(); 
	new-ExchangeServer" was run: "Value cannot be null.
Parameter name: Cannot get child of ADObjectId:	this is a GUID based ADObjectId.".

Any ideas what could be causing this? I haven't been able to find anything of significance while searching around...

Thanks!