can not show vms

I am wanna to connect my Vcenter to show one cluster all vms ,but it report error :Can't call method "serialize" on unblessed reference at /usr/lib/perl5/5.8.8/VMware/VICommon.pm line 2435.

I want to show cpu ,mem ,net ,io static ,and write all these data to mysql ,but I am stuck here .

 

#!/usr/bin/perl

use strict;

use warnings;

use DBI;

use utf8;

use VMware::VIRuntime;

use VMware::VILib;

my %opts = (

    cluster => {

        type =>"=s" ,

        help => "Enter the Cluster name" ,

        required => 1,

    }  

);

#connect the host

Opts::add_options(%opts);

Opts::parse();

Opts::validate();

Util::connect();

#script start

my $cluster = Vim::find_entity_views (view_type =>'ClusterComputeResource',

                                      properties => ['name'],

                                      filter =>{'name' =>Opts::get_option('cluster')});

my $vms = Vim::find_entity_views( view_type=>'VirtualMachine',

                                  properties => ['name'],

                                  begin_entity => $cluster );   

    foreach my $vm ( @{$vms || []} ) {

        my $vmname = '"' . $vm->{'name'} . '"';

        print $vmname;

    }  

Util::disconnect;

~