Hi @Tech Azur ,
With the wbadmin command the following should get the available copies/versions: wbadmin get versions
The Get-WBBackupSet is basically the same as the above command, but it seems you have the parameters wrong, here's an example on how to use it:
$BackupLocation = New-WBBackupTarget -VolumePath D:
$Backups = Get-WBBackupSet -BackupTarget $BackupLocation
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Best regards,
Leon