SRM 6.1 Unable to pair 2nd SRM site, odd error.

On a new installation of vCenter 6u1b and SRM, I'm unable to pair to the second site. I can add the PSC address (with default port 443), 'see' the site with matching SRM extension, connect with an admin acct, exchange certs, but then i get an odd error:

"SRM Server Cannot complete a pair Operation. The reason is: fault.lookup.fault.EntryNotFoundFault.summary.lookup.fault.EntryNotFoundFault.summary."

I've not been able to find anything on this specific error. Has anyone seen this before?

SRM version 6.1.0 build 3037005....

Thanks.