Dim pDoc As PartDocument = InvApp.ActiveDocument
Dim sFnDr As String = Replace(sFn3D, ".ipt", ".idw")
sFnDr = Replace(sFnDr, ".IPT", ".IDW")
Dim UseFile As Boolean = False
For Each Doc As Document In InvApp.Documents
If Doc.FullFileName = sFnDr Then
UseFile = True
Exit For
End If
Next