It is unlikely you can convert the newer .prproj projects from Adobe Premiere to the old .ppj format used in some of the previous version of the program. It may be possible to do it the other way though, but it is unlikely you could convert PPRPOJ to PPJ.
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.