Issue to create VSIX for a custom VS2010 AddIn

Hi,

I'm working on an AddIn for Visual Studio 2010 that generate files required to create a new business feature with my MVC 4 CMS : http://myprettycms.codeplex.com

I follow those instructions :

http://msdn.microsoft.com/en-us/library/dd885241.aspx

http://msdn.microsoft.com/en-us/library/dd393694(v=vs.100).aspx

Here my solution and it's dependencies.

When I click in the source.extension.vsixmanifest I obtain the following screen :

Then I click add content :

I don't find Visual Studio Add In

Can you tell me witch options I need ?

Thanks,

Laurent