Can't set BP on 'render' call

I have some functions used for Ajaxing whereby the function body is only a render call, like this:
def album_preview
        render :partial => "album_preview", :locals => {     #put a BP on this line
              ...
          }
end

I can put a BP on the indicated line but it never gets hit.  If I want to debug this, I typically have to add a line above the render call and put the BP there.  Am I missing something here or is this a bug?

Regards, Guy