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I am attempting to call code in a VSTO add-in.

The first place I landed in my searches was MS Walkthrough Calling Code in an Application Level Add-in

  1. I made a new VSTO project for Outlook.

  2. In this project I created the following Note Attributes same as in Walkthrough and added the RequestComAddInAutomationService

    enter image description here

  3. I then created a WPF application project and added my VSTO addin as a reference.

  4. The following is what happens. Please note that if I simply use the addin Object I can call my code, but I am unable to cast the interface. enter image description here

The first thing I have noticed is that This blog uses different attributes.

For anyone landing here and looking for a similar question in C# there are lots, this one being very similar however seems very user / computer specific.

So could anyone please help me to understand why I cannot cast the interface?

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darbid
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1 Answers1

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The problem is that the Interface was not registering properly for COM. Once the registration is done properly then the cast worked.

darbid
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