powershell - Powershell：不能将-pipelinevariable与get-netfirewallrule一起使用（动态参数）

Question

为什么我不能将 -pipelinevariable 与 get-netfirewallrule 一起使用？

PS C:\> Get-NetFirewallRule -PipelineVariable myfirewall | Get-NetFirewallPortFilter

Get-NetFirewallRule : Cannot retrieve the dynamic parameters for the cmdlet. Object reference not set to an instance of an object.
At line:1 char:1
+ Get-NetFirewallRule -PipelineVariable firewall | Get-NetFirewallPortF ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [Get-NetFirewallRule], ParameterBindingException
    + FullyQualifiedErrorId : GetDynamicParametersException,Get-NetFirewallRule