Apply formula cell by cell

I am trying to standardise a file like this:
Blank.jpg
I need to all the cell filled for further grouping.
I have tried with this formula:
@IF(MAIN_AGGREGATION == "",@GetPreviousValue("MAIN_AGGREGATION"),MAIN_AGGREGATION)
 Unfortunately it works for the first 2 rows only of Column AAA.
How I can get it work as if IDEA creates a virtual value to look up to give fill the blank cells?