Clicking on any booking takes me to a 'new' booking for today rather than the 'edit' of the existing booking

I've made some bookings but now when I click on a booking (link: http://<snip>...site...</snip>/moodle/blocks/mrbs/web/view_entry.php?id=0&area=1&day=1&month=9&year=2010 ) it takes me to a 'new' booking.

The problem appears to be the id value in the above URL which is always 0.