Hi Sarvan,

You mentioned you that wrote an add-in for Outlook Express using the Visual Studio shared add-in template, however Outlook Express does not support add-ins. Shared Add-ins target Office applications, and aren't compatible with OUtlook Express.

If your add-in is actually being used in Outlook, and doesn't seem to be working when you deploy it to another computer, you may be missing a dependency the add-in requires. Managed code add-ins (Shared Add-ins or VSTO add-ins) need to have the Office Primary Interop Assemblies (PIAs) installed on the computer. These may not be installed previously, so you should include the redistributable versions of these assmeblies as part of the add-in setup project. The 2003 PIAs can be downloaded here. You may also need to install the Extensibility PIA, which ships with Visual Studio and is not included in the PIA redistributables. You can check to see if this is already installed on the machine by looking at the GAC for an assembly named Extensibility. If it isn't there, you may need to include it in your installer and make sure it is registered in the GAC on the target machine.

If you are using any other assemblies or 3rd party libraries, you'll need to make sure those are included as well.

These are the most common issues that developers run into. If all of the dependencies are in place on the target computer, then you may need to debug why the add-in is not loading. You can check to see if any errors are occuring by opening the COM add-ins dialog in Outlook (tools -> Options -> Other -> Advanced -> COM Add-ins), and see if any errors are reported when the add-in was loaded.

--Ryan