I have an instructor who would like to use the dropbox in her account as a repository for students homework. A student can drag an item into the dropbox (normally a .jpg file) and a message appears that the file is being copied, but sometimes the file will appear in the instructor's dropbox (on the Mac server) and sometimes (more often) it will not. How can this work for some files but not for others? What can I check to pinpoint the problem? Could file size be a factor? These files I am testing with are not all that large (maybe 1-2 Mb).