Could I ask you to contact support with your details, so we can look into what's going on? You can do this by mailing f1support AT feral.co.uk, and they'll pass it on to us.
Could you also include a screenshot of the Finder's Get Info window for the installer application? You can do this by inserting your CD, selecting the installer, picking "Get Info" from the Finder's File menu, then using Cmd-Shift-4 to take a screenshot of that window.
That should help us identify which batch of CDs your copy belongs to, in case there's a problem with the SafeDisk system.
-dair
Zonic