I can read a meeting invitation e-mail OK - it says:
Found the appointment in the calendar 'Calendar'
at the bottom of the message.
When I try and accept the invitation I get the error below:
Unable to send item to calendar 'Calendar'. Invalid object
I have reproduced the problem with Evolution 2.12.0 on SuSE 10.2 and with Evolution 2.12.1 on Kubuntu 7.10.