Missing tkinter attributes after converting to py2exe executable

I have a Python 3.3 script which uses tkinter and tkinter.filedialog. The latter is being used in this particular line of one of the classes:

self.root_folder = os.path.realpath(tk.filedialog.askdirectory(**self.dir_opt))

The code runs well in IDLE. However, after being converted to a binary executable using py2exe, the program runs, but raises the following exception when trying to call the named line:

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Python33\lib\tkinter\__init__.py", line 1475, in __call__
    return self.func(*args)
  File "analyzer.py", line 403, in load_files
  File "analyzer.py", line 388, in select_root
AttributeError: 'module' object has no attribute 'filedialog'

The setup.py:

from distutils.core import setup
import py2exe

setup()
setup(
    console=['analyzer.py'],
    options={
        'py2exe': 
        {'includes': ['lxml.etree', 'lxml._elementpath', 'tkinter', 'tkinter.filedialog'],
         }
    }
)

I checked the contents of tkinter.__dict__ in the IDLE and binary versions. The executable lacks indeed the filedialog attribute, among some others. For instance:

**IDLE**          **EXE**
_varnum           _varnum
colorchooser        
commondialog      
constants         constants
dialog            
filedialog        
font              
getboolean        getboolean
getdouble         getdouble
getint            getint
image_names       image_names 
image_types       image_types
mainloop          mainloop
messagebox        
re                re

What am I doing wrong? I would be really grateful for your help.

PS. The very same problem seems to appear also when trying cx_Freeze.