i don't use DS  at all.  i got this error from using Poser installations of various and unassociated props.  they are not compressed files.  the only commonality seems to be that they use external geometry.   checking one of my own props, it works on the early version that had the geometry embedded but not the final version with the geometry externalized.  i also noticed that it didn't give me the error that the RDNA Organics prop did, whch alerted me that it couldn't find associated textures.  i just figured that they didn't have textures (being old and pretty basic), but now i see that it doesn't say anything in that case. 

i figured that it couldn't locate the geometry, but i wasn't sure whether that was a built-in limitation or not.  knowing it's supposed to actually find external geometry, and that it can't find textures, makes me think the issue is paths and the question you haven't asked me yet: what OS i'm on.  i'm not on Windows, i'm on Ubuntu 11.04.  i went poking at the code when i first had problems with the exporter options showing up because i thought that path problems might be the reason.  i thought it might not be finding some sort of file.  i didn't find anything obvious, but i'm still guessing that might be the issue.  if you relied on Windows backslash syntax for paths, that might explain issues i'm having.  it might also mean there would be a problem on Mac or any other non-Windows OS.  but that's really just speculation.