Frequency Simulator for an existing system

I have a partially conditioned building, I am trying to use the frequency simulator to tell me what percentage of the year the existing FCUs used will not meet the cooling demand and what the resultant temperature will be during this time.

The issue I'm having is that the option to state the FCU cooling Load (kW) is greyed out. so I can not define the existing system.

How do I get the simulator to allow me to fix this information.

Thanks

David Forster