The page you requested does not exist.
The trial premium pages are removed after the completion of the trial (they may stick around for a while until I get around to deleting the pages). So if you click on a link in the calendar for a past trial, it will likely be deleted. Same goes for links in the emails.
If you clicked on a premium link from a trial page, it is likely that the trial secretary has updated the premium and deleted the old version. Let me know and I will update the link. In any case, you will get the 404 page for the site where the premium was located.