What are the pre-requisite to run Balance exception Report?

Summary:

I tried to run Balance exception Report for Previous Period Gross Earning Difference, but the report is not showing the data.

June Month

Element - basic Salary = 2833.33

Element - Accommodation Allowance = 100

July Month

Element - basic Salary = 2833.33

Element - Accommodation Allowance = 200

Balance Exception report Should show the Accommodation Allowance variance as 100

But this report is not showing any data. Is there a specific setup get this requirement?

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