Problems with connector 0.90pre17 and Lightening 0.9.1pre1

I have installed: Thunderbird version 2.0.0.16 (20080707), Inverse SoGo 
connector 0.90pre17, Lightening (Inverse Edition) 0.9.1pre1 (build 
2008091718).   I am accessing calendars via CalDAV on a CommuniGate Pro 
5.2.3 server.

I get lots of these errors, seeming to relate to the new acl 
functionality.  Is there something I can do to fix?

Error: Components.classes[' <at> inverse.ca/calendar/caldav-acl-manager;1'] 
has no properties
Source File:

file:///home/ccoy/.thunderbird/27ek0itp.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/components/calDavCalendarModule.js 
-> 
file:///home/ccoy/.thunderbird/27ek0itp.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/js/calDavCalendar.js
Line: 2492

Error: uncaught exception: [Exception... "'[JavaScript Error: 
"Components.classes[' <at> inverse.ca/calendar/caldav-acl-manager;1'] has no 
properties" {file:

"file:///home/ccoy/.thunderbird/27ek0itp.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/components/calDavCalendarModule.js 
->

file:///home/ccoy/.thunderbird/27ek0itp.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/js/calDavCalendar.js" 
line: 2492}]' when calling method: 
[calISchedulingSupport::isInvitation]"  nsresult: "0x80570021 
(NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS)"  location: "JS frame :: 
chrome://calendar/content/calendar-item-editing.js :: openEventDialog :: 
line 274"  data: yes]