Vim: Supertab not working

I'm trying to make supertab working, it's not working when I press tab, not autocompleting python. Here's vimrc

set autoindent
set cindent
execute pathogen#infect()
syntax on
colorscheme flattr


set nocompatible
filetype off

set rtp+=~/.vim/bundle/vundle/
call vundle#rc()

" let Vundle manage Vundle
" required! 
Bundle 'gmarik/vundle'

" The bundles you install will be listed here

filetype plugin indent on

Bundle 'Lokaltog/powerline', {'rtp': 'powerline/bindings/vim/'}
Bundle 'tpope/vim-fugitive'
Bundle 'scrooloose/nerdtree'
Bundle 'klen/python-mode'
Bundle 'davidhalter/jedi-vim'
Bundle 'ervandew/supertab'


" The rest of your config follows here

" Powerline setup
set guifont=DejaVu\ Sans\ Mono\ for\ Powerline\ 9
set laststatus=2

cd ~/projects
map <F2> :NERDTreeToggle<CR>
map <Leader>nt :NERDTree %:p:h<CR>


" Python-mode
" Activate rope
" Keys:
" K             Show python docs
" <Ctrl-Space>  Rope autocomplete
" <Ctrl-c>g     Rope goto definition
" <Ctrl-c>d     Rope show documentation
" <Ctrl-c>f     Rope find occurrences
" <Leader>b     Set, unset breakpoint (g:pymode_breakpoint enabled)
" [[            Jump on previous class or function (normal, visual, operator modes)
" ]]            Jump on next class or function (normal, visual, operator modes)
" [M            Jump on previous class or method (normal, visual, operator modes)
" ]M            Jump on next class or method (normal, visual, operator modes)
let g:pymode_rope = 0

" Documentation
let g:pymode_doc = 1
let g:pymode_doc_key = 'K'

"Linting
let g:pymode_lint = 1
let g:pymode_lint_checker = "pyflakes,pep8"
" Auto check on save
let g:pymode_lint_write = 1

" Support virtualenv
let g:pymode_virtualenv = 1

" Enable breakpoints plugin
let g:pymode_breakpoint = 1
let g:pymode_breakpoint_key = '<leader>b'

" syntax highlighting
let g:pymode_syntax = 1
let g:pymode_syntax_all = 1
let g:pymode_syntax_indent_errors = g:pymode_syntax_all
let g:pymode_syntax_space_errors = g:pymode_syntax_all

" Don't autofold code
let g:pymode_folding = 0


" Use <leader>l to toggle display of whitespace
nmap <leader>l :set list!<CR>
" automatically change window's cwd to file's dir
set autochdir

let g:SuperTabDefaultCompletionType = "context"

You need to use omnifunc to provide the completion. It will pop up a menu to allow for completion. More information here.

In my .vimrc, I have the following lines set for Supertab:

let g:SuperTabDefaultCompletionTypeDiscovery = [
\ "&completefunc:<c-x><c-u>",
\ "&omnifunc:<c-x><c-o>",
\ ]
let g:SuperTabLongestHighlight = 1

Then enable the Python completion only for .py files:

autocmd FileType python set omnifunc=pythoncomplete#Complete