Workflow's WAS Management Service

Hello all - I'm having some troubles figuring out the magic that makes the WAS connection successful when attempting to publish to a remote server.

In the screenshot above, ATMA is the machine I'm publishing FROM, and WF76A is the machine I want to publish to.  Note that SDB is another remote workflow server and connects fine.  I've gone over all the settings on each remote server and am unable to find any obvious discrepancies.

I'd assumed that the Process Manager login info here was determining the authentication method, but I haven't had any success getting that to work:

So I'm hoping someone can shed some light on what I'm doing wrong here.

Thanks!