I was working on an Android project using Xamarin in Visual Studio 2012. I recently upgraded from an HDD to a SSD so I reinstalled Windows and all of my programs.
I could not get this working, initially. Tried removing everything (Mono runtime, app, etc.), but to no avail.
What did work was renaming my package, which was fine in my case since I haven't release my apk yet. Some ghost version is obviously still stored on my unit.