Verschachtelte Gruppenmitgliedschaften

Hi,

ich bastel grade ein kurzes Script um rekursiv die Gruppenmitgliedschaften eines Users abzufragen und bekomme diesen Fehler:

Get-ADPrincipalGroupMembership : Cannot convert 'System.Object[]' to the type 'Microsoft.ActiveDirectory.Management.ADPrincipal' required by parameter 'Identity'. Specified method is not
supported.
At C:\Users\she\Desktop\Untitled1.ps1:4 char:56+     ForEach ($group in (Get-ADPrincipalGroupMembership $ADPrincipal)) {+                                                        ~~~~~~~~~~~~+ CategoryInfo          : InvalidArgument: (:) [Get-ADPrincipalGroupMembership], ParameterBindingException+ FullyQualifiedErrorId : CannotConvertArgument,Microsoft.ActiveDirectory.Management.Commands.GetADPrincipalGroupMembership

Import-Module ActiveDirectory

function Get-NestedGroupMemberships ($ADPrincipal, [ref]$groupList) {
    ForEach ($group in (Get-ADPrincipalGroupMembership $ADPrincipal)) {
        if (-Not ($groupList -contains $group.name)) {
            $groupList += $group.name
            Get-NestedGroupMemberships ($group.name, [ref]$groupList)
        }
    }
    return $groupList
}

$groups = @()
Get-NestedGroupMemberships Sebastian_HH ([ref]$groups)

Wo ist mein Fehler?

Vielen Dank & Viele Grüße

Sebastian