how to list past events for a vmware virtual machine

Hi I'd like to see all migration events for a particular virtual machine, as we are trying to troubleshoot performance issues are being caused whenever DRS moves it between hosts.  

I have the following code which pulls off all the events for a specific virtual machine but it only returns the same number of events I can see in the vCenter html5 client, 41 events.

$fileName = $env:Temp + '\report.csv' 
$entity = Get-VM -Name my-vm 
$events = Get-VIEvent -Entity $entity -MaxSamples 1000 | Select CreatedTime,UserName,FullFormattedMessage | Export-Csv -Path $fileName -NoTypeInformation -UseCulture

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The vm has been around for a while so I would have thought there were more events than that.  In the vSphere flash based web client you could export all events between specific dates, I know there isn't that feature in the html5 client but is it possible to do this in the vSphere power cli?