Errors accessing published calendar

I'm using FM12Serv Adv on Lion server and have successfully published and connected the Sample Data. Zulu reports it has published my calendar OK but when attempting to subscribe via iCAL I get unexpected error -1. When I set up an iCal Account with Full Access FM creds I get 'Server responded with "500" to operation CalDAVAccountRefreshQueueableOperation.
In my Console I get the attached Error reported.
I read a post about Time formats, but I don't seem to be suffering that issue, nor are any of my Zulu fields Calcs, nor are the auto-enter calc text fields that they are based on any - though some are based on related fields.
In my Console I get the attached Error reported.
I read a post about Time formats, but I don't seem to be suffering that issue, nor are any of my Zulu fields Calcs, nor are the auto-enter calc text fields that they are based on any - though some are based on related fields.