plugging the twain device into the ts… I would suggest against it there are usually better solutions. I know this doesn’t answer your question, and I’m not sure why you sources don’t show up in twackers – I would check that the .ds files exist in the %windir%twain_32 dir on the ts and that the users have access to the directory. From there I would probably either step thru the twacker code or even better run filemon to see what files are getting accessed on the ts.
On the side, ts is odd enough on its own andfor that matter twain isn’t really something I would can clean but mixing in WIA which tends to muck with twain and twain solutions is my my experience just asking for trouble.
For our ts users we have all the twain stuff on the workstations where the users will be working and then an app on the ts that talks to each of the workstations to acquire stuff – it works pretty well.