[robot180]

We had that exact same problem and our site is hosted by Sevaa. I asked about it about a year ago and determined that we could not use http headers and other things for authentication. The server security simply did not allow it. One thing you can check is the permissions on the file, it didn't let certain things work when the permissions were set too high. CHMOD it to prevent write access from the group or public. If that does not work, I would say that the server security will not let you do it.

Another alternative is to use the server admin control panel and go to "protect web directories". You can add users and set a certain file or directory to require a login.