Password Protect Comment Feature not Working

I engaged the password protect comment feature in General Settings of the Administrator's Section, but visitors are still able to comment.

Is there something I missed here to prevent comments from spammers?

Thanks

Have a look at Lazarus

Thanks for the great suggestion.

I've tried it and it works beautifully. Lazarus was very easy to install, and all suggestions were clear.

By the way, Lazarus was one of the guest book programs I had on my short list to try, but for some reason I overlooked it. It turns out to be the best guest book so far.

Have a Great Day!