Disklavier

We have a Disklavier Mark III Series DC2A. I find no problem 
downloading midi music files and putting them on a floppy and 
playing them on the Disklavier, but today I tried to place the same 
midi files on a CD and it won't play in the Disklavier. They are the 
same midi files and both CD and floppy play fine on my computer but 
what is the difference with the Disklavier? Does the CD need some 
different form of file or special format?

FYI we bought the piano last Sept 2001 for our 35th Wedding 
Anniversary and my wife really enjoys playing it. I show friends how 
well I play, only I use the Disklavier. They are impressed with 
either one of our playing (I think my wife impresses them more 
though!).

Bill and Barb in PA.