Help - No module named Mailman

Hi,

I have installed Zope 2.5.1 src in /usr/local/zope/
and Mailman 2.1 (beta) /home/mailman following the installation instructions
under each of them. Formulator is installed.

When i start up zope and look at the product it is broken with the following 
message. 

Import Traceback
Traceback (most recent call last):
  File "/usr/local/zope/mail/lib/python/OFS/Application.py", line 531, in import_product
    product=__import__(pname, global_dict, global_dict, silly)
  File "/usr/local/zope/mail/lib/python/Products/ZMailman/__init__.py", line 7, in ?
    from Products.ZMailman import MailmanFolder
  File "/usr/local/zope/mail/lib/python/Products/ZMailman/MailmanFolder.py", line 13, in ?
    from ListManager   import ListManager
  File "/usr/local/zope/mail/lib/python/Products/ZMailman/ListManager.py", line 1, in ?
    from ZMailList import ZMailList
  File "/usr/local/zope/mail/lib/python/Products/ZMailman/ZMailList.py", line 6, in ?
    from FormManager import FormManager
  File "/usr/local/zope/mail/lib/python/Products/ZMailman/FormManager.py", line 4, in ?
    from Mailman import mm_cfg
ImportError: No module named Mailman

Please can someone tell me whats wrong and where i should look to correct this problem.

thanks 

godwin