dO YOU USE A mAC?

A MIDI file made on a Macintosh may likely have 128 extra bytes prepended to it (ie, a Mac Binary Header). If you remove those first 128 bytes (ie, all the bytes before you see the first 4 characters of 'M', 'T', 'h', and 'd') then you'll end up with a standard MIDI file. Use a hEXeDITOR program that edits binary (ie, not text) files to chop off the first 128 bytes (ie, characters).

Regards, John