Help with an unusual dev issue

[loismustdie]

I have a Windows app that uses TWAIN to scan images – it has all of the usual features. One customer who is using it has Fujitsu fi-4120C2dj scanners, and on some XP machines, that scanner does not show up in the ‘select source’ list, and it does not return in the list if I do a MSG_GETFIRST…MSG_GETNEXT enumeration. However, in other applications it does show up, and I wrote a test application using the exact same code as my original app and it shows up there too. I made sure that the supportedgroups tag is set correctly, so I’m not sure why this scanner isn’t reported to my app. Anyone have any ideas on why the source manager would not report this scanner to one application, but would to another (using the exact same TWAIN implementation code)? Thanks.

[gabe]

where and how are you looking for twain_32.dll? My experience with device’s not showing up has been people with roaming profiles / citrix / terminal server where your loadlibrary call is picking up a different dll than where the .ds is. What is the path to the .ds and what path are loading twain_32.dll from?
I’d double check with process explorer (sysinternals).

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[loismustdie]

I checked both the app that doesn’t work and the one that does – both are loading the TWAIN_32.DLL from the same place and if I enumerate all of the .DS files that exist, both apps come up with the same list. What I have discovered is that the scanner in question has a single .DS file that seems to expose two ‘sources’ – one that is WIA and one that is not. My app that is having the problem shows the WIA source, but not the non-WIA source. All of the other apps show both sources. Is there something that I’m missing that could be telling the source manager that it should only show the WIA source? I can’t find any differences between the implementation of the two apps or the way it is loading and communicating with the source manager.

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