I trying to simulate my building model with openstudio. My model use unitary air conditioners. I added na air loop HVAC but error occurred when run. Below is the error information.

information. Process exited with a non-zero exit code of: 1 Error report file indicates that the process did not complete successfully ManageSizing: Requested System Sizing but did not request Zone Sizing. System Sizing cannot be done without Zone Sizing Program terminates for preceding conditions.

I have no idea about this information.