Add-VDSwitchPhysicalNetworkAdapter error - "vmnic must be managed by the same VC Server"

I am using PowerCli 6.0 R3 on vSphere 6.0 update 1b.  I only have a single VM, my vCenter VM which is a Windows 2012 Server.  I also have 2 Dell ESXi servers.

I have successfully created a virtual Distributed Switch (vDS), 3 vd port groups and have added the first of 2 VMHosts to the VDS using PowerCli.

My problem occurs when I try to add my Host vmnics  which are (10GB NICs) to the VDS.  I get the following error:

     The PhysicalNicImpl - 'vmnic6' must be managed by the same VC Server that you are using to invoke this operation.

A code snippet is attached.  I appreciate any suggestions on what may be causing this error.  It feels like something in my environment.