expect.pm header

[amagana]

I am needing help with trying to insert a header for each server that gets the password changed in this script. I think I need a log file to identify where the script failed. But I am not able to get a header as recommended. I am getting this error: Global symbol "$system" requires explicit package name at ./tester-a line 7. Execution of ./tester-a aborted due to compilation errors. I am trying to insert a header into a log file for each server but I am just not able to get it to work,

#!/usr/bin/perl
use strict;

use Expect;

my $timeout = 60;
my $header = "\n\n======= $system =======\n"; 
my @servers = qw(
    Solaris-host
    Solaris-host
    Solaris-host 
    Solaris-host
);


for my $server (@servers) {
# do your thing with $server

    change_password($server);

 }

sub change_password {
            my $system = shift;

my $filename = "/var/tmp/expect_script.log"; 
my $ssh = Expect->new('ssh amagana@' . $system);



$ssh->debug(1);
$ssh->expect ( $timeout,
      [ qr/Password:/],
      [ qr/Are you sure you want to continue connecting \(yes\/no\)?/]
      );

if ($ssh->match() =~ m/Are you sure you want to continue connecting \(
+yes\/no\)?/)

 { 

$ssh->send("yes\r"); 

  }

elsif ($ssh->match() =~ m/Password:/ ) {

$ssh->send("mycurrentpassword\n");

}


$ssh->expect(60, '$');
$ssh->print_log_file($header);
$ssh->send("su - root\n");
$ssh->expect(60, 'Password:');
$ssh->send("rootpassword\n");
$ssh->expect(60, '#');
$ssh->send("passwd amagana\n");
$ssh->expect(60, 'New Password:');
$ssh->send("mynewpassword\n");
$ssh->expect(60, 'Re-enter new Password:'); 
$ssh->send("mynewpassword\n");
$ssh->expect(60, '#'); 
$ssh->close(); 
}