I'm afraid I don't have a vSphere 4.1 left in my lab.
But the problem is probably how the script links the disk Uuid with the Canonicxalname of the LUN.
Can you try the following for a VM that you know has a RDM ?
foreach($vminGet-VMMyVMwithaRDM){ $luns=Get-ScsiLun-VmHost$vm.Host-LunTypeDisk
$vm.ExtensionData.Config.Hardware.Device|where {$_.gettype().Name-eq"VirtualDisk"} |%{ if("physicalMode","virtualmode"-contains$_.Backing.CompatibilityMode){ $disk=$_.Backing.LunUuid
$luns| Select@{N="VM";E={$vm.Name}},CanonicalName,@{N="LunUuid";E={$disk}} |ft-AutoSize
} } }
In the output there should be a line where the 2nd part of the CanonicalName is present in the Uuid.
