Ensure that every Room / Room Part defined in the Quantity Calculation tab (that has a volume > 0) has at least one nozzle assigned to it. For example, if Room / Ceiling and Room / Main both have volumes, but  Room / Ceiling has no nozzle assigned to it, this error will occur because no agent is being discharged to protect that area. Nozzles can be assigned on the “Nozzle” tab of the Clean Agent Assistant, or via the wizard during the pipe network extraction.