Disklavier

Sorry to ask such a basic question but I have been reading various FAQ's and have tried to 
search the posts on this group but don't seem to be finding the answer to my question. I 
have a new DGC1 and have located several midi files on the net that I would like to write to 
floppy and play. Simple enough to down load the files and write to floppy on my Mac but 
when I insert the floppy into the Disklavier it indicates no songs found. Since these files are 
from various sites and are piano only I am under the impression that I don't have to do any 
editing or conversions with a midi program.

Thanks and happy holidays, John Isella