don't indent on nested namespaces in c++ mode

[Glen Stark]

Hi everyone.   I'm in Emacs 24.4.1.    I am able to get zero indentation 
on nested namespaces, if they are declared on separate lines, but not if 
they are on a single line.  

I have the following line in my configuration:

  (c-set-offset 'innamespace 0)

Which produces the desired result for:

   namespace foo{
   namespace bar{
   class foobar{};
   }

But when I have nested namespaces declared on a single line it
 produces the undesired:        
   namespace foo{ namespace bar{
       class foobar{};
   }


I've also tried the following (which I got from stack overflow), but it 
seems to have no effect whatsoever:
   (defconst my-cc-style
     '("cc-mode"
       (c-offsets-alist . ((innamespace . [0])))))

   (c-add-style "my-cc-mode" my-cc-style)


Can anyone explain what's going on, and tell me how to get the desired 
effect?

Many thanks, 

Glen Stark.