Program Error (Server Error 500)

<h1>Program Error (Server Error 500)</h1>
                  <hr />
             <p>
              <em>
              More information about this error may be available in the 
              server error log and/or program error log. 
              </em>
             </p>
             <hr />
               <pre>Can't use 'defined(@array)' (Maybe you should just omit the defined()?) at DADA/perllib/CGI.pm line 506.
Compilation failed in require at DADA/Template/HTML.pm line 47.
BEGIN failed--compilation aborted at DADA/Template/HTML.pm line 47.
Compilation failed in require at mail.cgi line 169.
BEGIN failed--compilation aborted at mail.cgi line 169.
</pre>