I've installed xapian via macports, so why does this python app tell me that xapian needs to be installed?

Question

I'm trying to run a python application on my system. When I try to execute it I get a traceback which ends with something saying I need to install Xapian. So I went ahead an installed xapian-core and xapian-bindings using macports. Then I tried to run the python application again, but got the same traceback. Any ideas about what I should do next? Is there some kind of additional xapian-python thingy I need to install? This kind of thing is all new to me.

I'm using Mac OS 10.6.3, Python 2.6.5 and Django 1.2.1

Here are the last few lines of the traceback I get:

File "/Users/nick/dev/ymtest/../ymtest/lib/haystack/__init__.py", line 46, in <module>
backend = load_backend(settings.HAYSTACK_SEARCH_ENGINE)
File "/Users/nick/dev/ymtest/../ymtest/lib/haystack/__init__.py", line 21, in load_backend
return __import__('haystack.backends.%s_backend' % settings.HAYSTACK_SEARCH_ENGINE, {}, {}, [''])
File "/Users/nick/dev/ymtest/../ymtest/lib/haystack/backends/xapian_backend.py", line 18, in <module>
raise MissingDependency("The 'xapian' backend requires the installation of 'xapian'. Please refer to the documentation.")
haystack.exceptions.MissingDependency: The 'xapian' backend requires the installation of 'xapian'. Please refer to the documentation.