Difficulty connecting two DNG instances as friends from different JTSes

I am prototyping this and have encountered difficulties. I have two separate hardware Windows machines, each running a fresh install of the evaluation version of CLM 6.0.5. They have different URLs and the two DNG instances have different context roots (/rm vs. /reqm). I initiated the Friend relationship from Rational instance A to B. Then I initiated a Friend relationship from Rational instance B to A. I logged in to the other system and approved the relationship and added a valid credential to it. The consumer keys match A to B and (separately) B to A. 

According to all the documentation I have read, everything is configured as it should be. 

I noted the other similar threads on this subject but they all seemed to either still be unanswered or be related to a resolution in a version of DNG that was released between then and now. Because I am running the latest GA version of DNG, I thought I would start a new thread. 

When I attempt to add the remote DNG instance as an Association to a DNG project area, I receive the following message. (Note that all pop-up boxes are allowed, I was fully logged in to both DNG instances within the same browser session, and both DNG instances have valid self-signed SSL certificates that have been onboarded to the browsers.) 

The message:

Thank you!