Stylesheet Problem

I downloaded and ftp’d the un-zipped files (in tact) to my server. I went and logged in to my blog. Under ‘presentations’ an opened ‘themes’. Under ‘available themes’ I saw the listings of the new downloaded themes and all are listed ‘style sheet is missing’ on all 4. I checked my host files and the sheets are there. Nothing was left out of the ftp transfer. What happend and how do I fix it. (I downloaded these files 2x and the same thing happened each time).