No file here:
http://www.adventuregamestudio.co.uk/AGS-3.1.2.zip
Sorry if it has already been reported.
3.1.2 is an outdated version, so I'm not sure why you'd expect that to still be online? AGS-3.2.1.zip is the latest CJ version. Where is AGS-3.1.2.zip still being linked from?
Oh cool, 3.2.1 works. So yeah, it's linked with the wrong version number here:
http://www.adventuregamestudio.co.uk/AGS.aspx --> Older versions and other downloads >> AGS 3.2.1 plain zip file
Good spot, thanks -- I'll fix it in the next update.