With rails.vim, why do commands not work when the active buffer is empty or is not a file that is part of the rails project?

If I do not have a file opened from the project rails, I'm working, I can not use any rails.vim commands, such as :Rcontroller, :Rmodel, :Rview(I get the error: Not editor command).

Also, if I try to use :Rconfigor :Rrouteswhen I do not have a rails open file, I get an error message: Not editor command :: Rfind application.yml.

I am using pre-fab vim config, so I assume I need to track down the problem there? Or is this just the way rails.vim is designed to work?