[Interest] Add-in can't register help in VS2012

[Bob Hood]

I'm getting:

"Cannot register qt VS2012 help! (error code: 101)"
"Cannot register qt5vs VS2012 help! (error code: 101)"

when I attempt to install the Qt5 Visual Studio Add-in (1.2.2) into VS2012
Update 4.

Any ideas what might be causing that?