If your results aren't what is expected, then you need to start debugging, try...

use CGI::Simple;
use Data::Dumper;

my $q = CGI::Simple->new();
my %input = $q->Vars;

print $q->header('text/plain');
print Dumper(\%input, \%ENV, \$q);
[download]

Send your form data to this using a browser, it will print out a representation of all the data sent to the script %input, all the environment data %ENV and the CGI::Simple object.

See if the script is being fed what you expect it to, if that doesn't help, then post the results here to give us all a bit more context.