OTBI Pivot Table IFNULL Function

Summary

Could anybody provide guidance in using the IFNULL function to display zeros in a pivot table as opposed to blank cells?

Content

I have created an analysis using the “Workforce Management - Worker Assignment Event Real Time” using the measure "Assignment Event"."Transfer In Count", a time dimension, department and business unit in order to track the movement of employees over a year. The data is displayed in a pivot table as per the attached screenshot.

I have been trying to display zero values for months for which there were not any moves by using the formula IFNULL("Assignment Event"."Transfer In Count", 0), however months without any data (null) are not returning zero. I have also attempted to use a CASE statement as an alternative to IFNULL.