There is no way how you could convert rar to mp3, i.e. rar archive to mp3 music, unless you meant to extract RAR archive that contains MP3 music. In that case use any file archiver that supports RAR format, which pretty much covers rar to mp3 conversion.
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.