This could be your issue. Hard to tell without seeing your code.

From CGI.pm - a Perl5 CGI Library, the CGI.pm online documentation

Most HTML tags are represented as lowercase function calls. There are a few exceptions:
The <param> tag used to pass parameters to an applet conflicts with CGI's own param() method. Use PARAM() instead.

In reply to Re: cannot load applet using Perl/CGI by Hero Zzyzzx
in thread cannot load applet using Perl/CGI by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


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