I tried to export some of my Wings 3D objects in obj format, in order to put them on the 3dvia.com website. But it seems that the .mtl file that goes together with the obj one is not ok, and the import fails.
I finally found that the origin of this issue is the Ke parameter in the wings mtl file : when I remove it, there is no more trouble.
i didn't found this parameter on http://www.fileformat.info/format/material/ , does that mean that it is not supposed to be here ? Maybe it should'nt be included in the mtl file export at all ?
I also reported the issue to the 3dvia website.