Automating Word and Excel

I have an Excel add-in which I use to do a large amount of data analysis, and then transfer the data to tables in a Word template. I would now like to insert some AutoText saved in the template before populating the tables, but I can't find the syntax to do this. I keep getting error code 450 - Wrong number of arguments or invalid property set.

Here's the code I'm using:

VB Code:

Dim WordApp As Word.Application
    Set WordApp = CreateObject("word.application")
    WordApp.Visible = True
    With WordApp
        Documents.Add Template:= _
        "C:\Documents and Settings\all users\Templates\rxtemptest.dot" _
        , NewTemplate:=False, DocumentType:=0
 
        .Selection.Goto what:=wdGoToBookmark, Name:="PlaceMark"
        .ActiveDocument.AttachedTemplate.AutoTextEntries("Temp1").Insert Where:=Selection.Range, RichText:=True
         End With
    Set WordApp = Nothing

Can someone point me in the right direction? If it is not possible to use Excel to insert AutoText, can someone tell me how to call a procedure or macro saved in the Word template that will insert the AutoText?

Thanks, Lee