cue to mp4 conversion does not make sense actually, since cue file is just a description file and not multimedia file. Maybe you were looking for something else and this is just a typo, but otherwise we do not know how to convert cue to mp4.
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.