Subscriptions module appears fine, but it just diesn't work

First of all, the checkbox for "Automatically subscribe to threads in which you post." doesn't save it when you check the box.
And if you subscribe directly it is registered but it doesn't send any E-Mail to notify.
So I don't understand why this module is offered for Drupal 4.6.x, unless it diesn't work for 4.6.5 which I'm using, at least they should put a notice.