Not all music files showing up on mp3 player

I have a similar problem but different.

I used iMac to copy the music file in iTunes to my 16G SDHC disks.  Those files are in mp3 formats.  I later deleted these files and re-create the mp3 files from iTunes to the disk.

While I can see the files in PC or iMac, when inserted to my car audio player (CED2000), I can only see those files that I deleted earlier and a few files from the the last copying action that I did (I just re-create a few more music file from iMac and turn them into .mp3 files.

I am wondering why

  1. my audio in car continues to show those music files (in mp3) that I have deleted from the SDHC card

  2. The mp3 files that I re-create from iMac …converting from m4a files to mp3 files using iMac, did not show in the audio player

Wonder what went wronng…