Adding .mp4 audio

I have an audio file that I synced using iTunes. It shows up in iTunes as added. I select sync but it does not show up in the "effects", "audio" selection. The file should have been added, but is not to be found. It was originally coded in .m4v but I noticed you can only use .mp3 and .mp4 files. I converted it to .mp4, but it is still not showing up in the add audio track.
I noticed in the list of tracks, it only has .mp3 and .wav files. It does not have any .mp4 files.
1 person has
this question