I'm in the basic settings for my website. I'm trying to connect as a specific user. I enter the user's username and password. I say OK. I test the connection. It works. Then I click OK on the main Basic Settings dialog and it gives me this error:

I am returned to the dialog with the Alias highlighted.

What does it mean that the value is outside the expected range? Range of what? What IS the expected range? What does it have to do with the Alias?