My VSTO 3.0 Outlook addin doesn’t load



[Sorry if this isn't the right forum for this... technically not VBA but this
is the closet forum I could find]

I'm trying to diagnose why my Outlook plugin written in C#/VSTO 3.0/VS 2008
doesn't load after being installed.

The plugin works awesomely on my development machine, which has Visual
Studio 2008 installed. I can't expect all my users to have all the
prerequisites though so I went through these steps to write an installer:

I installed the add-in on a fresh Windows XP SP 2 machine with a fresh
install of Outlook 2007. It installs all the prereqs ok (.NET 3.5, VSTO 3.0
runtime, Windows Installer 3.1, 2007 PIAs). Outlook starts but the add-in
isn't run. If I go to the Add-ins tab in the Trust Center, I see my add-in in
the "Inactive Application Add-ins" section with the message "Not loaded. A
runtime error occurred during the loading of the COM Add-in.".

Not sure how to find the specific error so I can fix it.

The reg keys look ok. Under
HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\BlahAddin I see
Description, FriendlyName, LoadBehavior (set to 3 until it fails after which
if becomes set to 2), and Manifest.

Tried the VSTO_SUPPRESSDISPLAYALERTS environment variable trick and then
launched Outlook from the command line but no output came out.

I have remote debugging more or less working but I'm not sure what to look
for. I don't see my DLL loaded when I attach to Outlook, but then again maybe
managed DLLs don't show up the same way in VS.

Any other ideas on next steps I could follow to produce a specific error I
can diagnose?


(Cross-posted to Stack Overflow, but still haven't figured this out: )


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