explore DOM Objects of HTML documents

I am trying to explore the DOM structure of a HTML document. For this purpose I am writing a script in Powershell.

First approach:

$ie.Document.getElementsByTagName('*') | foreach {
     $_.TagName
}

works fine. Now I want to explore more in depth. Therefore I wrote a function:

Function AnalyseTree
{
  Param ([string]$TreeElement)
  write "Called"
  $TreeElement.TagName  
}

$ie.Document.getElementsByTagName('*') | foreach {
     AnalyseTree($_)
}

this one does nothing, it prints "called", but not any more the Tagname. When I say only $TreeElement I get DomObject. I can make however the situation worse, when I define different the function, that it say not even DomObject when I write $TreeElement only.

Function AnalyseTree
{
 $TreeElement = $args[1]
  write "Called"
  $TreeElement.TagName  
}

What I am doing so wrong ?

Thank you very much for every hint

and maybe, someone already wrote a function which does what I am trying to do ?

Thx a lot

Eryk