Unable to get License Expiration details

Hi All,

I am unable to get the license expiration details as it shows blank

$LicenseManager= Get-view LicenseManager

$LicenseAssignmentManager= Get-View $LicenseManager.LicenseAssignmentManager

$LicenseAssignmentManager.GetType().GetMethod("QueryAssignedLicenses").Invoke($LicenseAssignmentManager,@($null)) |

Select EntityDisplayName,

    @{N='Product';E={$_.Properties | where{$_.Key -eq 'ProductName'} | select -ExpandProperty Value}},

    @{N='Product Version';E={$_.Properties | where{$_.Key -eq 'FileVersion'} | select -ExpandProperty Value}},

    @{N='License';E={$_.AssignedLicense.LicenseKey}},

    @{N='License Name';E={$_.AssignedLicense.Name}},

    @{N='Used License';E={$_.Properties | where{$_.Key -eq 'EntityCost'} | select -ExpandProperty Value}},

    @{N='Total';E={$_.AssignedLicense.Total}},

    @{N='ExpirationDate';E={$_.Properties | where{$_.Key -eq 'expirationDate'} | select -ExpandProperty Value}}

#| Export-Csv c:\license_report.csv -NoTypeInformation -UseCulture