I don't see anything particularly wrong with the RelocateVM_Task() parameters. Can you confirm a few things for me:
1) You're using the latest vSphere SDK for Perl 5.1
2) Is the VM located in any Resource Pools or Folders (nested?) or is it just in the root of your vSphere Cluster
3) Have you tried with any other VMs, could you test with a dummy powered on VM (just create a dummy VM and power it on and see if you're getting same error)
4) How many disks does the VM have, I assume it's all stored together with the VM configuration file?