Add a vCAC Host Handshake Alert

I am trying to write some workflows for vCAC, but first I need to add the vCAC host to vCO. When I try to run the 'Add vCAC Host' workflow it dies right away with the error 'handshake alert:  unrecognized_name'

This is running against vCAC 6.1 using vCO 5.5.2

Any thoughts on the fix?