Some possibilities:
- You didn't yet set the permission of the file once it was uploaded. Only you can see it (while using your hosting account) until you give it public read and execute permission. Some hosts do this automatically, others do not.
- From the error message, it appears that the browser does not have a file name to look for. Are you using the correct url?
- Does your home page have the required filename?
- Has the site had time to activate the file? I had one web server that activated new files and updated changes only once a day.