The only reason you get "Document contains no data." is because Netscape requested a document and the server response was zero bytes. If you look in your access_log file you will likely see a series of code 200, size 0 entries. In a standard log file, these are the two numbers following the "GET /..." text.

What you probably want to do is debug your script, and make sure that it always returns something, even if that's an error page.

Also, it's Perl, not PERL. Like UNIX, you could say it's case-sensitive.