When you save a proposal with Type set to Venues, Sprwt looks for other bookings at the same venue on the same date: (1) other proposals at that venue whose status is included in Catering > Settings > Proposals tab > Reports > Event Status to Include (default Fully Paid Or Partially Paid) and whose start/end times, together with the other proposal's start time, land in the same block of the venue's weekly schedule, and (2) online catering orders that reserved the venue (new, paid or in-progress orders) whose time slot overlaps your start-end range. If either is found, the proposal is not saved and the message This venue is already booked for the selected date and time. Please choose another venue. is shown. Change the time, the date or the venue and save again.