VB.NET-对非共享成员的错误引用需要对象引用（WindowsIdentity.Groups属性）

   Error    1   Reference to a non-shared member requires an object reference.  
                (on WindowsIdentity.Groups)

    Public ReadOnly Property Groups As IdentityReferenceCollection
    Get
        Dim irc As IdentityReferenceCollection
        Dim ir As IdentityReference

        irc = WindowsIdentity.Groups
        For Each ir In irc
            MsgBox(ir.Value)
        Next

    End Get
    End Property

    Dim myWindowsIdentity As New WindowsIdentity

    Error   2   Overload resolution failed because no accessible \'New\' accepts 
                this number of arguments.