why won't this file transfer to iPod?

i had a purchased tune that i modified (i wanted to up the volume for a certain segment). i did uploaded it back into iTunes where it sits as an AAC audio file.

it will not transfer to iCloud which is OK by me. apparently, the playlist it is in won't either. also not a problem.

however, this song will not load to my iPod and i cannot figure out why. the rest of the playlist loads fine.

hints? suggestions?