abbrev mode not working

[Florian Lindner]

Hello,

on emacs 24.3.1 I have trouble using the abbrev mode.

emacs -Q
M-x python-mode
M-x abbrev-mode

typing "pdb", nothing happens.

Though my ~/.emacs.d/abbrev_defs contains:

;;-*-coding: utf-8;-*-

(define-abbrev-table 'python-mode-abbrev-table
  '(
    ("pdb" "pdb.set_trace()" nil 0)
   ))


If starting emacs without -Q behaviour is the same. Saving the abbrevs 
to the global-abbrev-table does not make a difference either.

What could be wrong there?

Thanks!