Thu Dec 23, 2004 2:10 pm by Argh
Well, if you read the release notes, I specifically said that Alpha wasn't compatible with SP- the reasons for this are long and complicated, and probably won't ever get fixed, unfortunately- I really, really tried, but never did get them working right. So think of SP as a "sandbox mode" where you can practice flying, buy the ships and test them, etc., but can't do Missions (for that matter, you'll never see any bad guys spawn, either).
To do Missions, you need to start a MP server on your computer through FLMM, and then you can do missions in MP, where they work just fine. Your computer will have to work a little harder, but it's not that great a strain (unless you're Outcast, who's still using Win98 with less than 128MB of RAM)...