wanabegates

I want to convert open IPod files that I have purchases to MP3 or WMA files and have them play on my Windows Mobile equipped phone. When I say open iPod files, I mean they are .m4a files that are not locked as I purchased them that way. My confusion lies in that, the conversion goes well and I can play the files on my laptop with no issue. I can also open the files one at a time on the phone in the Medea player application (similar to the one built into windows). I also have a Music only player on the phone that normally indexes new music that I drop in to a folder that I purchase from eMusic. I don't have to modify a thing, just drop em in and go. When I drop the converted files in, they don't even show up. Does anyone have any clue how to fix this? Is it a matter of bit rate? I'm clueless on this one.