why wont it play

I just got my 6820 and started putting midi's on it all files open in nokia pc suite,play and upload to phone but quite a few wont play once on the phone it say's "Can't open file"?

I use nokia pc suite because i can't get anything else to work.

I open up regular midi i got from web in nokia sound converter and select optomize size and preview and upload to phone and it ups a .mid file to phone
some work some don't what's the trick.


Also how to i make my own midi's ringtons from my cd's and mp3's?