Hi,
If you don't specify a registry location when initializing the add-in
engine, then Mono.Addins will use a global shared add-in registry.
When using the global registry, add-ins must specify a namespace (add-
in namespace, not C# namespace) to avoid name collision with other
applications/add-ins. So, to fix this issue you have two options:
1) Specify a namespace for the add-in (see
http://monoaddins.codeplex.com/wikipage?title=The%20add-in%20header&referringTitle=Reference%20Manual)
2) Use an application specific add-in registry.
Lluis.