First you should trace out the error log path and see what kind of error it is showing. Than as suggested by monks, you can download the below module from CPAN and use it.

use CGI::Carp qw(fatalsToBrowser); use strict;

or if you have more number of lines in your code and to check whether a particular function is been working or not you can see by writing the following 2 lines of code and test.

print "Content-type:text/html\n\n"; print "here";