Vim formatting using gg=G with xml
===

I have a correctly formatted xml file, and following the command given as an answer here:

http://stackoverflow.com/questions/2355834/auto-format-c-file-in-vim 

I am trying to auto indent my file to display correct nesting.

Before I tried to use this command I set the file type to xml using `:set ft=xml`
as the file I started with has an extension of `.mm`, and also `:set nowrap`.

Here is my ~/.vimrc file:

    syntax on
    set history=1000
    set smartindent
    set tabstop=2
    set shiftwidth=2
    set expandtab

How come when I issue `gg=G`, I get a message saying `54 lines indented`, yet my file remains un-nested?