And, there is a quick response on that thread on ClimatePrediction forum link... Wow, this has been happening for years, people are complaining, and somehow it is not getting fixed? What a bummer...
Here, that response, quoted:
"It IS a known issue here, which was looked into a few times, possibly a couple of years back now.
From what I remember, our site responds to BAM requests, but BAM doesn't get a reply.
It's apparently something to do with cpdn using a separate url for the front page (non-BOINC), to the one used for the rest of the site.
I think that the solution is to create accounts here first.
But you've already done that, and I don't know of a solution for "not attaching" to this account.
Wild guess:
Detach (or whatever), from BAM, create & attach accounts manually, and THEN convert to using BAM.
But don't run any work before getting BAM working. It gets jealous and deletes the pre-BAM work.
And perhaps a BAM using will show up who knows just how to make it work.

"