once you have already uploaded a zip simfile, if you delete just the stepfile(in management) [whether or not you have a thumbnail makes no difference(thought to be the cause of the error)] You get the message "Invalid audio type. Upload zips only." Before deleting the file to be updated, I checked the link and it showed the zip as a .mp3 link. I think the feild is requiring an mp3 even though it's saying it requires a zip. Anyways, I have to reupload the whole kit, but this doesn't seem like it would bee too hard an error to fix synth.
