What stupid thing have I done or missed?

I get this error:

Traceback (most recent call last):
  File "/usr/local//lib/python2.4/site-packages/MoinMoin/request.py", line 1439, in __init__
    RequestBase.__init__(self, properties)
  File "/usr/local//lib/python2.4/site-packages/MoinMoin/request.py", line 156, in __init__
    self._load_multi_cfg()
  File "/usr/local//lib/python2.4/site-packages/MoinMoin/request.py", line 313, in _load_multi_cfg
    self.cfg = multiconfig.getConfig(self.url)
  File "/usr/local//lib/python2.4/site-packages/MoinMoin/multiconfig.py", line 162, in getConfig
    config = _makeConfig(configName)
  File "/usr/local//lib/python2.4/site-packages/MoinMoin/multiconfig.py", line 99, in _makeConfig
    cfg = configClass(name)
  File "/usr/local//lib/python2.4/site-packages/MoinMoin/multiconfig.py", line 499, in __init__
    self._check_directories()
  File "/usr/local//lib/python2.4/site-packages/MoinMoin/multiconfig.py", line 644, in _check_directories
    raise error.ConfigurationError(msg)
ConfigurationError: 
data_dir "data" does not exists, or has incorrect ownership or
permissions.

Make sure the directory and the subdirectory pages are owned by the web
server and are readable, writable and executable by the web server user
and group.

It is recommended to use absolute paths and not relative paths. Check
also the spelling of the directory name.

Traceback (most recent call last):
  File "/usr/local//lib/python2.4/site-packages/MoinMoin/multiconfig.py", line 160, in getConfig
    config = _config_cache[configName]
KeyError: 'wikiconfig'

Additionally cgitb raised this exception:
Traceback (most recent call last):
  File "/usr/local//lib/python2.4/site-packages/MoinMoin/failure.py", line 143, in handle
    display=request.cfg.traceback_show,
AttributeError: 'RequestCGI' object has no attribute 'cfg'


which would seem pretty obvious to fix, except that:
pwd is /var/opt/wiki/
drwxrwx--- 4 www-data www-data 4096 2007-10-29 22:24 ./
drwxr-xr-x 3 root     root     4096 2007-10-29 21:27 ../
drwxrwx--- 7 www-data www-data 4096 2007-10-29 21:27 data/
drwxrwx--- 3 www-data www-data 4096 2007-10-29 21:27 underlay/
-rw-rw---- 1 www-data www-data 5890 2007-10-29 21:39 wikiconfig.py
-rw-rw---- 1 www-data www-data 1846 2007-10-29 22:24 wikiconfig.pyc



from httpd.conf:

Alias /wiki/ "/var/opt/wiki/"
ScriptAlias /moin "/usr/local/share/moin/server/moin.cgi"



from /var/opt/wiki/wikiconfig.py:

data_dir = './data/'