This article will discuss the most likely reasons that a direct reservation cannot be created.
The room/beds with zero rates will not be available for booking.
Please make sure to add rates if you want to sell this room by following these instructions: How to Add / Edit Base Rates

While reviewing the room information on the availability matrix, ensure that no restrictions exist that would prevent the reservation from being created, such as Minimum Night Stay or Maximum Night Stay.

Access the Availability Matrix and make sure that the room is not Blocked or Closed to Arrival or Closed to Departure:

If you have negative availability for one room but positive for another one, like here:

In the case above, the total availability for your property will be calculated as: -1+1=0, and this is the reason why none of the rooms will be available for a direct reservation, even though you can see that there is 1 room available.
If you have an overbooking setting disabled here: Rates and Availability->Availability Matrix->Settings-> Overbooking Settings you will not be able to add a reservation when there is no availability
You can find more about overbooking features here: Overbookings features in Cloudbeds

The system works like this in order to prevent overbookings. If one of your room types is overbooked, you would want to have availability in another room category in order to accommodate the guest.