Samsung SCH-A670

I've downloaded a number of midi files to use as ringtones and never had a problem until now. I found a midi file that I liked that was only ~20K in size. I can play it over and over again on my PC using Windows Media Player. But when I send it to my phone via a Pix message, it always arrives corrupted according to my phone. All I can do is delete it. I downloaded the original midi file to my PC again and played it in WMP again to make sure it really worked and it still won't download to the phone. Any ideas? AFAIK the midi file is a freebie.