Calculating Ds for cooling condition

Hello, I am trying to determine whether or not I am calculating Ds correctly. I previously had every zone set to 100% Ds, but I was told that Ds = the minimum supply air flowrate/maximum supply air flowrate. For example we are using dual fan dual duct VAV units and the maximum cooling cfm for a room is 210 cfm and the minimum is 63 cfm. Should Ds then be: Ds = 63/210 = 30%? Or should I just have Ds set to 100%? When I had all the values to Ds set to 100% the sheet worked, but when I changed it to the equation I got the error message Critical zone needs more ventilation. Any help would be greatly appreciated. Thank you for your time, William Beechinor