There is zero variance. All of the values for your input field are likely the same.
This tool was designed to work with a field that contains a variety of values. The count of the binned polygons is used for analysis. If the values for binned features are all 1, for example, there is no variation in the values, and the computed variance will be zero. When the variance is zero, results cannot be computed.
Choose a location with a variety of counts. Values are calculated using binned values; change the size of your bins or time steps to change the calculated values.