Can't instantiate a COM object written in C# from VBA (VB6 ok)

Question

Using VS 2008, here is my COM object

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Wi         


        

Answer 1

This works for me from VBA... I tried it using Word & Excel 2003 (SP3).

I'm not sure what you mean by "production" machine. Because this is a "client" application and must be executed on the client using Excel.

If you're automating Excel on the server and triggering this "interop" through a VBA call, you're asking for trouble :)

Assuming that by production, you mean the client machine where user will be using the Excel template / doc, these are the following pointers:

1. Make sure you have the appropriate .Net framework
2. That you have latest service packs for Office
3. Try ascertain if this is a rights issue.

If you're feeling adventuristic, you could use a process explorer [from Microsoft sysinternals site] to see what're the DLLs loaded and where exactly are you getting the error and compare it to the list on your dev box.

Hope this helps.

Answer 2

RC1, I tested this with your code from VBScript and from within Office 2007's Excel, everything works fine.

Since your able to create the COM object from within a VB6 form we should assume that your .net framework is ok. Can you rule out issues with VBA? Can you create a .vbs file and put this in it:

Dim o As Object  
Set o = CreateObject("Test9.COMINT")  
o.Init "A", "B"

Save the file and double click it. If you get an error, then I would think there is an issue with it being registered, if you don't get an error, then I would look at Office and VBA and see if something is missing or not installed properly.

Another option is to add a reference to COM object and use early binding? I think you might need to export a typelibrary first, but you should be able to add a reference and simple new the object up.

Answer 3

rc1 is correct in that this is a .net error, thrown when Office can't decide which version of the Framework to use. However, Office isn't throwing a wobbly simply because it's spoilt for choice. There is a bug in how Office 2003 interacts with .net 2.0.

Installing the fix from Microsoft (KB908002) is a more flexible way of solving the problem than by forcing Excel to run in a particular version of .net.

See also: http://www.biopdf.com/guide/trouble_shoot_microsoft_office_2003.php

Answer 4

I'm going to answer my own question, hopefully to spare others the hours of tedious drudgery I have just endured.

If you get this, it is because the .NET based COM assembly can't find the .NET framework

The solution is simple. Create a file containing the following

<?xml version="1.0"?>
<configuration>
  <startup>
   <supportedRuntime version="v2.0.50727"/>
  </startup>
</configuration>

Call it "Excel.Exe.Config" and place it in the same directory as "EXCEL.EXE"

Problem solved!

Answer 5

installing the follow fix will resolve this issue http://www.microsoft.com/downloads/details.aspx?FamilyID=1b0bfb35-c252-43cc-8a2a-6a64d6ac4670&displaylang=en