A. If an input column in an expression contains null data then no results will be calculated for any output columns for the null records.  This is regardless of whether the input column is used in the calculated expression for that column but only when working in Multivariate mode.  Multivariate mode requires that records must contain a valid data value for all input columns otherwise the output columns will record null values.  To enable the calculations to run independently of each other uncheck the Multivariate mode box so that univariate mode is used.