Fill Null Values in Script

[#1]

When I use NULLASVALUE, and select the null value as 0, the script doesn´t fill automatically the rest of the formulas that include the variable with the NULLASVALUE with the respective value? How can I fill missing values with different null values?

I set the null value as 0, and select for the variable 'Frecuencia Volumen´ and ´Recencia Volumen´ so if the data is missing the 'Ponderación Volumen' Should be 0.1 because the variables are 0. But the script doesn´t fill this variable with 0.1. How can I do that or fix some different values in case of null values? Thanks