Outlook.Explorer.SelectionChange event called only once

I attach to Outlook.Explorer.SelectionChange event. Event handler makes a call to an assembly that retrieves some data from web services. After one call to that assembly my event handler is no longer called when S开发者_Go百科electionChange occurs.

Any ideas?

This seems to be somehow related to the assembly itself, not what it is doing. Simply creating any class from that assembly breaks events in my add-in.

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Apparently this is a common mistakes newbies like myself do. Kudos to whoever wrote this article.