I have exactly the same problem. The command llive version works perfectly but any attempt to install the add-in throws an unknown error on load.
Just like Vincent I am using VS 2010 on Win 7 x64.
I have tried building from source with the latest set (545c2664560a) and it's still the same problem. Also tried the packaged releases
v220.127.116.11.3, v18.104.22.168.2, and a couple of earlier ones too just for good measure but so far no success.
In fact I tried debugging the add-in but the error seems to occur before I can even get to the point of debugging. I started to wonder if I was missing some sort of dependency but I have the Visual Studio SDK, Java runtime and SDK, and everything else I
could find that looks like it might even be a remote dependency. I am starting to think it's related to the way WOW64 has a seperate set of registry keys and if nobody has a solution soon I will go digging in that direction because this is exactly the tool
I want my team to use - assuming we can make it work of course.