You say that you can see the data uploading but can't see the data when you look on your ISP. Are you actually looking at the raw directories and files on your ISP (e.g. via a telnet client), or are you trying to look for the uploaded file/page on your Web site? The reason I ask is that FTP files and Web pages often live in different portions of the directory structure, so the file may have been uploaded correctly, just not to where you expect it. Also, some web hosts will allow you to upload files into a directory, but not, in general, to view/download files once they are uploaded. This is a security precaution intended to prevent script kiddies from using your ftp space as an illegal file-exchange service. In any case, and as others have pointed out, you want to be really careful with security issues when you're allowing uploads to your site for any reason.

Good luck!