File or Assembly Cannot be Loaded Error

Question

I am working on a Setup program which creates a .msi file. There is a CustomAction program associated with it which is written in C#. There are three COM object references made in this CustomAction program which are necessary in order for it to work. They are as follows.

1. Active DS IIS Namespace Provide (C:\Windows\System32\inetsrv\adsiis.dll)
2. Windows Script Host Object Model (C:\Windows\System32\wshom.ocx)
3. NetFwTypeLib (C:\Windows\System32\FirewallAPI.dll)

As added information, following are the tasks I use these DLLs in my program for.

1. To set MIME settings for a particular file type.
2. To create a desktop shortcut to a folder.
3. To register a program as a firewall exception

.

Now, here is my problem. When I rebuild the C# program and execute the CustomAction program from within Visual Studio, it works fine and I can get the above three tasks done like a charm. However, when I actually build the .msi and try to execute it and install the program on my system, it gives an error. I'm using a Japanese OS so it gives the error in Japanese so I'll try to translate the error message in to English as best as I can. The error is something like this:

*

File or assembly 'Interop.IISOle, Version = 1.0.0.0, Culture = neutral, PublicKeyToken = null', or one of its dependencies could not be loaded. Cannot find the file specified.

*

This particular error message is given because it relates to the first dll (adsiis.dll) because it is the one which contains the IISOle namespace. Similarly it gives error messages relates to all the three COM objects which I made references to from my program. Now what I can understand from this is, somehow when this code is inside the .msi file it cannot find the appropriate COM objects. I'm really confused why this happens as the Setup gives the same error when I try to install the program even on the same machine which I used to code the CustomAction. Funnily it executes flawlessly from withing Visual Studio Interface. Please do help me with this. Thanks in advance!

Note that I'm working on Windows Vista Business, but I need my Setup to be able to install on a variety of Windows OS ranging from Windows Server 2003 to Windows 7.

Answer 1

Anton, finally I found out what was wrong.

When I reference, for instance, dsiis.dll then Visual Studio places an Interop module, namely Interop.IISOle.dll inside the bin directory of my CustomAction program. Which is where the CustomAction.exe can also be found. It does the same process when I reference the other two COM objects; wshom.ocx and FirewallAPI.dll. But my actual setup program which is written using Wix copies this CustomAction.exe to some other directory and the .msi uses that particular CustomAction.exe file. The problem occurs since Interop.IISOle.dll (and the others as well) cannot be found there. (The error message said what I needed to look for from the beginning it seems; I was foolish not to look for it but thinking there might be bigger problems)

So this is what I did. I instructed the Wix project to copy those Interop DLL files to the same place where the CustomAction.exe which is used by the installer resides. That solved the problem so easily.

I'm totally a newbie when it comes to Wix, plus we needs to use the CustomAction for 2 and 3 because of some reasons.