
Note that this is just a test and accordingly I didn't bother with a few things. However, either doing things the right way with the appropriate subdomain/top level domain combination for e-mail address or, as I supposed at first it was, the email address with which I registered to the control panel, I get the result below. The same happens for the password (same as the one for control panel or different). I have a few notions of combinatorics so I know I'm going to spend a long time just trying combinations of the various parameters.

Might I say that this error page isn't particularly helpful. One cannot guess at the erroneously filled field by just looking at the phrase. Some general filling-in guidelines would also smooth the learning curve, methinks.
Anyway, even if it's just a hardware problem that's causing this, many thanks in advance for any help.