Without the code, it's impossible to find the error. Try this to debug it:

#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper::Concise;
use Net::SSH::Perl;

my $host = 'host';
my $user = 'user';
my $pass = 'password';


my $ssh = Net::SSH::Perl->new(
          $host, 
          debug => 1,
          protocol => 2,1
);
$ssh->login($user, $pass);
$ssh->session_id;
$ssh->config;
print Dumper $ssh;

exit;
[download]