It appears that you actually cannot convert MS Access .accde files to anything else, even the the original database, or just export the data to an Excel spreadsheet (.xls), which means accde to xlsx conversion is not possible.
ACCDE format is designed to be view-only executable that allow users to access and view the database, but not edit it. There is really no way how to reverse the process unless you have access to the original database.
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.