You cannot convert .ses files (sessions) from Adobe Audition to FLAC, or any other audio format. The sessions contains just metadata for Audition project and not the actual audio data. If you want to convert the audio, you would need to do that for the data references in the project.
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.