99% of the time you are getting an error message because you are trying to book the wrong site at the Hipcamp. Usually we only opt in one site at the Hipcamp for the photography booking, even if there are multiple sites. The site available for your photography booking is shown when you claim the assignment. If you're having trouble with this and don't know which site you were supposed to book, please email us at fieldscouts@hipcamp.com. Note: we can switch the opted in site to another one if your Host agrees.