Error: a("body").on is not a function
Its seems, that this issue is because your theme is used the old version of jQuery (v.1.4.2).
Please, download the latest version of jQuery and integrate it into your actual theme,
just use the latest version of jQuery from WordPress installation (just comment loading of the jQuery from the theme and the Booking calendar will add load of the jQuery from your wordpress installation (of course, recheck that this installation also have to be up to date)).
Here is more detail.
I am not sure that its the same issue,and not really understood what type of issue you are have. If the previous suggestion will help you ,so then fine, if not, please explain it more detail. You can also post it at the support board here, for more fast getting respond.