DWF files are made as publish only version of the original content, so while you can view (import) these files to many CAD/3D modeling tools, it is not possible to either alter or convert these to any other format.
Some tools can try to recover the assets, but it might not work, or work just partially. It's better to try to obtain the source from which the .dwf files were exported in first place.
This conversion entry was verified by us and conversion was flagged as wrong or not possible.
Usually this happens when the conversion would try to convert different types of data between each other, such as audio to image, or it is not possible because incompatibility between programs, caused by closed file formats, very limited support etc.
If you find entry that you feel is flagged as bad wrongly, please tell us in the discussion below with as much as information as possible so we can fix it.