Recently purchased a Used Kenwood MP5039U and get it installed in my car.

Overall was fine except having some issue with the USB.

Tried two 2gb USB drive formatted to FAT32 & 16, dump a few mp3/wma/aac files in it.

Plug into the HU, prompted with "NA FILE", tried all the file in the drive, around 10 of it.

All returned with Error "NA FILE"

Any advise?

well it's a secondhand electronic device so possibilities are there for the internals to go haywire. Try seperately with mp3 alone and try to use a working thumbdrive.
From the HU's spec it should support wma/mp3/m4a.

Tried using a clean formatted pendrive with just mp3 files, it failed, same error...Nvm anything will go back to seller as he ask me to inform him anything go wrong...

Seller has responded on the issue as advise by his son the HU USB was sometime works, sometime not working.
Thread closed.