Hi

I'm automating Word in my VB.NET Windows Forms application, and I'm hitting
a problem when the application is used with Word 2000.

To access the Word functionality, I created a reference to the Word 97 type
library (we support all versions from 97 onwards). I then have some code
that creates a new Word document, puts some text into it and then calls the
SaveAs method of the document object to save the document with a given
filename. A cutdown version of the code is here - basically I have removed
the majority of the text insertion stuff for clarity...

Dim strFilename as String = "C:\MyTest.doc"

Dim WordApp as New Word.Application
Dim WordDoc as Word.Document = WordApp.Documents.Add()

WordDoc.Range.InsertAfter("Some text")

WordDoc.SaveAs(CObj(strFilename))
WordApp.Quit()

This works fine on the majority of machines, including my development
machine (Word 2002 SP1 on Win2k). However the SaveAs fails when run on a
machine running Word 2000 SR1. The error reported is that an object
reference is not set to an instance of an object.

The confusing thing is that I have done this previously in C++, and it works
fine on the very same machine. I have checked that the document object is
set to a valid instance, and it is, so I'm guessing the problem lies in one
of the parameters. All the parameters other than the filename however are
optional, and are left blank.

In the C++ code, the optional parameters have to be supplied, so I pass
variants, with the type set to VT_ERROR and the value set to
DISP_E_PARAMNOTFOUND. I did wonder if the optional parameters that I had
omitted in VB.NET were being treated differently, so I wrote an automation
server app with a method that had optional parameters, to see what was
passed. VB.NET passes a variant exactly the same as I have to in the C++
code - type VT_ERROR and value DISP_E_PARAMNOTFOUND.

So, I'm a little confused as to what is going on. Any ideas would be most
welcome, as Google has failed me!

Best regards

Martyn Pearson
Barbour Index