This doesn't help much, other than lead me to believe you are simply typing the URI incorrectly into your browser location bar. What you are asking is why does the web server think the files are missing. So we need to confirm that the web server is not seeing the files. The easiest way to do this is to temporarily remove any index.* files in that directory. Then by browsing to that directory, you will see a listing of all the files the web server sees. You should then be able to see if you are misspelling the filenames are if you even uploaded them to the right place. Don't forgot to upload your index.* files again.
Perl / MySQL / HTML+CSS