I have trueSpace 6.6 and 7.6, and Deep Exploration 3.5. All can export .STL format models. I've tried uploading the same model, exported from each of these apps. No dice. I'm not sure if the issue is with a corrupt format, or a damaged/too thin model. Will have to try something else to verify. Anyways, the model export matrix on http://www.shapeways.com/tutorials/supported-applications, claims that trueSpace is supported, with a Collada export that is "native". I don't see a Collada export option in either versions of trueSpace. What am I missing?