Strange Wiki error maybe related to ical server (caldavd)

Wiki and Calendarserver were running fine. Then I added a second website via server admin. Wiki was not anymore reachable via site1 or 2. site1 was SSL, site2 was without (port 80). Then I deleted both and set up a new one. Wiki etc is enabled in that setup.
Looking at Wikid error log I see:

2007-11-04 10:12:17+0100 [HTTPChannel,14,129.187.41.62] Exception rendering:
2007-11-04 10:12:17+0100 [HTTPChannel,14,129.187.41.62] Unhandled Error
Traceback (most recent call last):
File "/usr/share/caldavd/lib/python/twisted/web2/channel/http.py", line 412, in processRequest
self.request.process()
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 291, in process
d.callback(None)
File "/usr/share/caldavd/lib/python/twisted/internet/defer.py", line 239, in callback
self._startRunCallbacks(result)
File "/usr/share/caldavd/lib/python/twisted/internet/defer.py", line 304, in _startRunCallbacks
self._runCallbacks()
--- <exception caught here> ---
File "/usr/share/caldavd/lib/python/twisted/internet/defer.py", line 317, in _runCallbacks
self.result = callback(self.result, *args, **kw)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 318, in _getChild
return self._handleSegment(result, res, path, updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 358, in _handleSegment
child = self._getChild(None, newres, newpath, updatepaths=updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 318, in _getChild
return self._handleSegment(result, res, path, updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 358, in _handleSegment
child = self._getChild(None, newres, newpath, updatepaths=updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 318, in _getChild
return self._handleSegment(result, res, path, updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 358, in _handleSegment
child = self._getChild(None, newres, newpath, updatepaths=updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 314, in _getChild
result = res.locateChild(self, path)
File "/usr/share/wikid/lib/python/apple_wlt/GroupServer.py", line 125, in locateChild
if not groupIsATeam(self.groupname, theRequest.headers.getRawHeaders('x-forwarded-host')[0]):
exceptions.TypeError: 'NoneType' object is unsubscriptable

2007-11-04 11:39:47+0100 [HTTPChannel,18,129.187.41.62] Exception rendering:
2007-11-04 11:39:47+0100 [HTTPChannel,18,129.187.41.62] Unhandled Error
Traceback (most recent call last):
File "/usr/share/caldavd/lib/python/twisted/web2/channel/http.py", line 412, in processRequest
self.request.process()
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 291, in process
d.callback(None)
File "/usr/share/caldavd/lib/python/twisted/internet/defer.py", line 239, in callback
self._startRunCallbacks(result)
File "/usr/share/caldavd/lib/python/twisted/internet/defer.py", line 304, in _startRunCallbacks
self._runCallbacks()
--- <exception caught here> ---
File "/usr/share/caldavd/lib/python/twisted/internet/defer.py", line 317, in _runCallbacks
self.result = callback(self.result, *args, **kw)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 318, in _getChild
return self._handleSegment(result, res, path, updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 358, in _handleSegment
child = self._getChild(None, newres, newpath, updatepaths=updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 318, in _getChild
return self._handleSegment(result, res, path, updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 358, in _handleSegment
child = self._getChild(None, newres, newpath, updatepaths=updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 318, in _getChild
return self._handleSegment(result, res, path, updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 358, in _handleSegment
child = self._getChild(None, newres, newpath, updatepaths=updatepaths)
File "/usr/share/caldavd/lib/python/twisted/web2/server.py", line 314, in _getChild
result = res.locateChild(self, path)
File "/usr/share/wikid/lib/python/apple_wlt/GroupServer.py", line 125, in locateChild
if not groupIsATeam(self.groupname, theRequest.headers.getRawHeaders('x-forwarded-host')[0]):
exceptions.TypeError: 'NoneType' object is unsubscriptable

Any hints what could case that problem?