I have been updating the website as things have changed (new pics etc.) The latest update is to the Crew Page, but as I was checking it I noticed that the Booking Calendar (on the Booking Page - a bought-in script) is not showing up (on any browser).
Not sure without seeing how you added the calendar but what I do see is that there is no Div with the id: AvailabilityCalendar1 on the non working page in the source code.
They have a good range of scripts for calendars (and other stuff) and I found them helpful with all the amends and tweaks to the script necessary to satisfy my customer.
There may be better booking calendars out there - I found loads when I was looking around - so it will be worth your time to do a bit of research.