We are using the appointments plus plugin to take appointments for our escort site:
However its still in development so you'll have to use this link:
(just a heads up there are some partially nude photos but nothing too explicit)
That being said, you'll notice that if you try to make an appointment you won't be able to do so.
To my knowledge I have set up everything correctly, but I could be mistaken.
My only thought is that our business hours are from 9:00 am until 4:00 am and I'm wondering if this is causing conflict. (I tried setting the hours to 12 am to test but it didn't seem to make a difference in order to get the plugin to work)
However if this is a conflict we need a way around it as these are our business hours.
I look forward to your reply.